USMLE step 1 important points

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USMLE STEP-1 POINTS MADE EASY

2000 + Important exclusive points

Mostly repeated in USMLE part 1

Made easy to understand

Note : there are many things like this that we have at our institute and we

distribute all this for our students so ill be posting some of sample pointswhich is quite enough to understand about our material

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Addison's disease Adrenal insufficiency can cause hyperpigmented skin due to an increase in

melanocyte-stimulating hormone (MSH). Patients will have electrolyte imbalances due to

aldosterone deficiency and experience severe reactions to minor illnesses due to cortisol

deficiency. Diagnosis is confirmed using the ACTH stimulation test.

Cushing's syndrome Patients with Cushing's syndrome will have characteristic features such as

central obesity with a buffalo hump, moon facies, peripheral muscle wasting, purple striae,

easy bruising, and psychiatric disorders. This disorder is due to glucocorticoid excess.

Diagnosis is confirmed with the dexamethasone suppression test.

Diabetes mellitus Although DM causes polyuria and polydipsia, it cannot account for the patient's

other symptoms.

Hemochromatosis This metabolic disorder, which is also known as bronze diabetes, is an autosomal

recessive disorder resulting from increased absorption of iron from the GI tract.

Iron accumulates in several organs, including the pancreas (causing diabetes),

heart (causing cardiomyopathy), testicles (causing testicular atrophy), skin

(causing increased pigmentation), and liver (causing cirrhosis). Treatment

consists of regular phlebotomy and deferoxamine, an iron chelator.

Wilson's disease This autosomal recessive disorder is caused by impaired copper excretion. Signs and

symptoms include tremor, ataxia, dementia, and psychoses. The classic

ophthalmic finding is Kayser-Fleischer rings (brown-pigmented rings at the edge

of the cornea) from copper deposits. Treat with penicillamine, a copper

chelator.

AcetazolamideA

cetazolamide is a carbonic anhydrase inhibitor. Members of this class of drugs aregenerally not used to treat hypertension, as the diuresis is self-limiting within

two to three days. The mechanism of self-limiting diuresis is as follows: By

inhibiting carbonic anhydrase in proximal convoluted tubules, acetazolamide

causes increased urinary excretion of bicarbonate. As the body bicarbonate level

decreases, excretion slows even with continued diuretic use, and the diuresis

becomes self-limiting.



Amiloride This potassium-sparing diuretic works in the late distal tubules and the cortical collecting

ducts by inhibiting reabsorption of Na and secretion of K and H. It would be

useful for treatment of hypertension, but it does not have any effect on

reabsorption of calcium. Furosemide is a better option, as it would also helpreabsorb calcium and, therefore, not make the patient's osteoporosis worse.

Clorothiazide This thiazide diuretic inhibits Na/CL cotransported in the early distal convoluted

tubules. It is useful for treatment of hypertension, especially in a patient with

osteoporosis, as it increases calcium reabsorption from urine by an unknown

mechanism.

Furosemide Furosemide is a loop diuretic that works on the medullary ascending loop of Henle by

inhibiting Na/K/2 CL cotransport that accounts for 20% to 25% of reabsorption

of Na. Downstream sites cannot compensate for the sodium excretion, which

makes these drugs very efficacious and useful for treatment of hypertension.

Loop diuretics cause decreased reabsorption of calcium from urine, however,

and they may worsen this patient's osteoporosis condition. In fact, loop

diuretics are often employed for treatment of hypercalcemia (as induced by

malignancy, for example).

Mannitol Mannitol is an osmotic diuretic. Most of the filtered solutes will be excreted in larger

amounts unless they are actively reabsorbed. Osmotic diuretics are not

indicated for treatment of hypertension, but may be used to decrease cerebral

edema and intraocular pressure.

Cavernous sinus This sinus contains cranial nerves III, IV, V, and VI as well as the internal carotid

artery. Cranial nerves VII and VIII do not pass through here.

Floor of the middle cranial fossa in the trigeminal dural cave The middle cranial fossa contains anumber of structures that carry many important vessels and nerves, including

the cranial nerves associated with ocular motility (III, IV, and VI) and sensation

(V). However, this portion of the fossa does not contain any nerves that would

explain the patient's unilateral hearing loss.



Internal auditory meatus This structure holds the facial and vestibulocochlear nerves (cranial nerves

VII and VIII) as well as the labyrinthine artery. Because the patient has difficulty

with the facial muscles of both the upper and lower face, we know that the

lesion in cranial nerve VII must be peripheral instead of central (in which only

the lower portion would be involved). Cranial nerve VII also gives rise to the

preganglionic parasympathetic fibers that will innervate the lacrimal gland,

which forms tears. A lesion in cranial nerve VIII in this location also explains

unilateral hearing loss.

Jugular foramen This foramen transmits cranial nerves IX, X, and XI as well as a portion of the internal

jugular artery. These structures are not responsible for the patient's symptoms.

Superior orbital fissure This fissure transmits cranial nerves associated with ocular motility (cranialnerves III, IV, and VI) as well as the ophthalmic nerves and veins. A lesion here

would not explain the patient's auditory symptoms or the lack of abnormalities

in ocular motility.

Leukotrienes productionAspirin, like NSAIDs and acetaminophen, blocks COX-1 and COX-2 enzymes

in the arachidonic acid metabolism. However, the lipoxygenase enzyme

pathway is not blocked, thus funneling most of the arachidonic acid through the

lipoxygenase pathway that produces leukotrienes (LTB, LTC, LTD). LTs are

responsible for increased bronchial tone (i.e., bronchospasm), causing the

respiratory distress symptoms observed in this patient.

Phospholipase A2 deficiency A deficiency in phospholipase A2 would mean that no arachidonic acid is

produced. If there is a deficiency in arachidonic acid, then aspirin has no

negative effect and would not cause respiratory distress.

Prostacyclin production Prostacyclins are by-products of arachidonic acid metabolism via the COXenzyme pathway. Because aspirin blocks both COX-1 and COX-2, no PGIs will be

produced. In addition, PGIs are responsible for decreased bronchial and vascular

tones, as well as decreased platelet aggregation.



Prostaglandin production Prostaglandins are by-products of arachidonic acid metabolism via the COX

enzyme pathway. Because aspirin blocks both COX-1 and COX-2, no PGE/PGF

will be produced. Prostaglandins are responsible for decreased bronchial and

vascular tones.

Thromboxane production Thromboxane is a by-product of arachidonic acid metabolism via the COX

enzyme pathway. Because aspirin blocks both COX-1 and COX-2, no TXA will be

produced. TXA, however, can increase bronchial tone and result in

bronchospasm, leading to respiratory distress.

Acting out Acting out is the expression of unacceptable thoughts in actions. An example might be

violent behavior toward an inanimate object.

Denial A reality is avoided. This is a very common reaction to hearing any life-changing news.

Displacement Unacceptable thoughts are placed on another person or object.

Isolation Emotions are divorced from events. This response is often experienced after being a

survivor of a plane crash, bombing, or cataclysmic fire.

Rationalization Unacceptable thoughts are replaced by logical reasoning, explaining why something

happened.

Frameshift mutation This type of mutation is caused by the addition or deletion of a base pair, which

changes the reading frame. The resultant protein is usually nonfunctional.

Large segment deletion mutation This type of mutation is usually due to an unequal crossover in

meiosis. Alpha-thalassemia is an example.



Missense mutation The patient has sickle cell anemia and is in a sickle cell crisis. This condition is

caused by a point mutation in which glutamic acid is replaced with valine. The

result is an unstable hemoglobin molecule.

Nonsense mutation This type of mutation causes the insertion of a stop codon in the reading frame.

The resultant protein is usually shorter and nonfunctional.

Silent mutation In this mutation, the codon is changed but still specifies the same amino acid. There is

no adverse reaction from this type of mutation.

Left middle cerebral artery Blockage of this vessel would cause, among other effects, right-sided

hemiplegia and sensory deficits mainly of the face and arms, a right visual field

defect with inability to gaze to the right, and aphasia.

Right middle cerebral artery Blockage of this vessel would cause, among other things, left-sided

hemiplegia and sensory deficits mainly of the face and arms and left visual field

neglect with inability to gaze to the left. In addition, there may be neglect of the

left side.

Left anterior cerebral artery This vessel supplies the medial aspects of the left hemisphere. Blockage

may cause a weak, numb right leg (and possibly arm symptoms in milder forms).

The face is typically spared.

Right anterior cerebral artery This vessel supplies the medial aspects of the right hemisphere.

Blockage may cause a weak, numb left leg (and possibly arm symptoms in milder

forms). The face is typically spared.

Left posterior cerebral artery This lesion presents as a right-sided visual field deficit, alexia without

agraphia (if the corpus callosum is spared), and possible defects in naming

colors.



Right posterior cerebral artery This lesion typically presents as a left-sided visual field deficit along

with left-sided sensory loss if the thalamus is affected. There may also be left-

sided neglect.

Left posterior inferior cerebellar arteryThis lesion would cause infarction of the lateral medulla and

inferior cerebellar surface, causing vertigo with vomiting, dysphagia, and

dysarthria. In addition, there would be nystagmus looking toward the left, left

sided Horner's syndrome, and loss of pinprick sensation on the left side of the

face and on the right side of the trunk and extremities. This condition is also

known as Wallenberg's syndrome.

Right posterior inferior cerebellar artery This lesion would cause infarction of the lateral medulla and

inferior cerebellar surface, causing vertigo with vomiting, dysphagia, anddysarthria. In addition, there would be nystagmus looking toward the right,

rightsided Horner's syndrome, and loss of pinprick sensation on the right side

of the face and on the left side of the trunk and extremities. This condition is

also known as Wallenberg's syndrome.

Colorless colonies on MacConkey agar; oxidase positive; blue-green pigment on nutrient agar

Pseudomonas aeruginosa causes pneumonia, urinary tract infections, sepsis,

and hot tub folliculitis. Pseudomonas grows in water and can withstand many

detergents and disinfectants. Pyocyanin gene product gives purulent material a

bluish hue, while pyoverdin is seen as yellow-green with ultraviolet light.

Ultraviolet light may be used to assess cutaneous infection by Pseudomonas in

burn patients. Pseudomonas does not ferment glucose.

Colorless colonies on MacConkey agar; urease positive; blackens triple sugar iron agar Proteus

commonly causes urinary tract infections. Liberation of ammonia by urease

increases urine pH, which increases the potential for struvite stone

development.

Colorless colonies on MacConkey agar; oxidase negative; no gas on triple sugar iron agar Shigella is

characterized by its virulenceonly 100 bacteria must be ingested to develop

shigellosis. Person-to-person acquisition is common, via fingers, flies, food, and

feces. Symptoms begin as fever and abdominal pain, progressing to watery



diarrhea, which later consists of blood and mucus. No rash is associated with

shigellosis. Lactose is not fermented, as evidenced by colorless colonies on

MacConkey agar.

Colored (pink) colonies on MacConkey agar; urease positive K lebsiella is found in the large intestine,

soil sources, and water sources. The thick capsule is characteristic of this

bacterium. K lebsiella causes pneumonia in the elderly, diabetic patients,

patients with chronic obstructive pulmonary disease, and alcoholics. Pink

coloration on MacConkey plates indicates lactose fermentation. Current jelly

sputum, necrosis, and abscess formation are commonly associated with

pneumonia caused by K lebsiella.

Colored (pink) colonies on MacConkey agar; metallic green sheen on EMB agar E sc heric hia coli causesdiarrhea, urinary tract infections, hemolyticuremic syndrome, and meningitis.

Pink coloration on MacConkey plates indicates lactose fermentation.

A great increase cardiac output and GFR Prazosin does not greatly affect cardiac output, renal

perfusion. or GFR; rather, its action is to decrease arterial and venous resistance.

There is some effect but it is not a dramatic one

A high risk for syncope Syncope often is a side effect of alpha inhibitors. It is often associated with the

first dose, but prazosin is usually given at night to prevent this side effect.

Increased tone in the smooth muscle of the bladder and prostate, leading to decreased urinary

retention The tone in the prostate gland is decreased, which leads to the

decrease in urinary retention.

An association with bradycardia Alpha blockers are associated with tachycardia. Beta blockers

decrease the sympathetic tone on the heart, thereby reducing chrontopic

stimulation to the heart. The alpha blockers affect only the resistance of the

blood circuit, so in response to a relatively low blood pressure the sympathetic

nervous system stimulates the heart to beat faster and harder.



Chagas disease This disease is caused by infection with T rypanosoma cruzi . It is spread by reduviid

insects, typically in South America. A nodule, or chagoma, forms at the site of

the insect bite. Later complications include megacolon, megaesophagus, and

cardiac abnormalities (conduction block).

Gonorrhea While disseminated gonorrhea can cause joint pains, infection with the responsible

organism is better known for its monoarticular manifestations. In addition, it is

not associated with cranial nerve palsies.

Lyme disease Borrelia burgdorferi is a tick-borne spirochete that is classically associated with

erythema chronicum migrans, often missed by patients. This patient manifested

other signs, such as her malaise and arthralgias. Her facial droop is also a classic

finding for Lyme disease. A tetracycline will be helpful in eradicating the disease.

Rocky Mountain spotted fever This disease is caused by infection with a tick-borne rickettsia

(R. rickettsii ). It presents with headache, fever, and a generalized skin rash

(palms and soles first).

Sleeping sicknessAlso known as African trypanosomiasis, sleeping sickness is not found on the

Eastern Seaboard of the United States. Fever, lymphadenopathy, joint pains,

and CNS changes are characteristic.

HIV This patient is presenting with Pneumocystis carinii pneumonia, which is very often the way HIV

is diagnosed. Unfortunately, this patient likely has a CD4 count less than 200,

which means that his infection is quite advanced. First-line treatment is to get

an ABG and, if the P O2 is less than 70, start steroids, along with high-dose IV

trimethoprim-sulfamethoxazole.

Pasturella multocida This infection is often associated with pain and limited motion to an extremity,

which can lead to osteomyelitis.



Hypertensive emergencyThis condition is typically seen in patients who have end-organ damage,

such as retinal changes, mental status changes, or renal dysfunction. It does not

specifically present with a picture typical for pneumonia.

Plague The plague (Y ersinia pestis infection) typically presents with tachycardia, tender lymph nodes

(particularly inguinal), high fever, malaise, and myalgia. It can also be associated

with a lobar process on CXR.

Pulmonary tuberculosis While the malnourishment fits this diagnosis, the severe hypoxia is more

indicative of PCP.

Chloroquine One would not use chloroquine against chloroquine-resistant species of Plasmodia.

Iodoquinol This luminal amebicide may be used against E ntameba histolytica, but not against any

species of Plasmodia.

Mefloquine Mefloquine is used for prophylaxis in cases where a patient is predicted to be exposed to

chloroquine-resistant P. falcipartum, as in this case. A blood schizonticide, it has

no effect on extraerythrocytic stages of the malarial parasite. Therefore,mefloquine does not act against P. ovale or P. vivax , which left this patient

vulnerable to malaria caused by infection with one of these species.

Pentamidine This drug is used for trypanosomiasis and in Pneumocystis carinii pneumonia, but not

against malaria.

Primaquine Primaquine is used for prophylaxis in cases where a patient is predicted to be exposed to

P. ovale or P. vivax . This patient was treated with a drug that would decrease

her chances of getting malaria via P. falcipartum. Primaquine is a tissue

schizonticide that works by forming cellular oxidants.



Pyrimethamine This antifolate drug blocks folic acid synthesis in susceptible protozoa. A blood

scizonticide, it acts primarily against P. falcipartum. This drug is not used for

prophylactic purposes.

Eating undercooked beef is usually how the infection occurs. T aenia saginata (beef tapeworm) is the

cause of infection when undercooked beef is ingested.

In addition to residing in the colon, the infectious agent can migrate to the lung. F ilariaris,

Pargonimiasis, and E c hinoccus are helminths that have been known to migrate

to the lung. E nterobius resides only in the colon.

It is diagnosed by looking for proglottids in the stool. Proglottids can be found in the stool of persons

infected with T aenia saginata and T aenia solium (pork tapeworm)

It is diagnosed with the Scotch-tape test. With E nterobius vermicularis, female worms leave the anus

at night, lay eggs, and die. This causes severe anal itching. Placing Scotch tape

over the area at night will pick up the eggs, which can then be examined under a

microscope to confirm the diagnosis.

E nterobius is transmitted via the fecal-oral route

Continue frequent breast feeding and take an antibiotic. Frequent breast feeding has been shown to

shorten the clinical course of mastitis along with antibiotic treatment. The

organisms will be killed in the infant's stomach, and the antibiotic must be safe

for infants.

Stop nursing and let the infection heal. This will likely lengthen the clinical course and possibly cause

abscess



We will set you up for a mammogram today. There is no current indication for mammogram. Also,

due to the density of the breast tissue, the study would not find many small

cancers if they existed.

Amyotrophic lateral sclerosis ALS is characterized by both upper and lower motor neuron loss in the

spinal cord, brainstem, and motor cortex. It is a chronic, progressive,degenerative disease.

Conversion disorder Conversion disorder is a psychiatric diagnosis for people with multiple symptoms

that cannot be explained by a medical cause. There must be psychological issues

related to the onset, although the patient is not conscious that these reasons

are why the symptoms have occurred.

Multiple sclerosis MS is a demyelinating disease characterized by multiple neurologic complaints that

are set apart by time and space, and that cannot be explained by a single lesion.

It is typically relapsing-remitting, with symptoms that abate for a period of

months to years before other symptoms appear. It typically is worsened by heat.

Myasthenia gravis MG is an autoimmune disease characterized by antibodies that bind to post-

synaptic acetylcholine receptors. It commonly affects eyesight and causes

fluctuating fatigable ptosis or double vision. Symptoms typically worsen during

the day.

Parkinson's disease Parkinson's disease usually occurs in people older than 50 years. It is caused by

dopamine depletion in the substantia nigra. Typical symptoms include

bradykinesia, resting tremor, shuffling gait, stiffness, and fatigue.

Adenosine phosphoribosyl transferase Adenosine phosphoribosyl transferase is an enzyme used in

the salvage pathway of purines. It is involved in the final step of the pathway,the conversion of adenine to AMP.

Hypoxanthine-guanine phosphoribosyl transferase Hypoxanthine-guanine phosphoribosyl transferase

(part of the salvage pathway for purines) deficiency leads to LeschNyhan

syndrome, which is the clinical picture presented in this case. This is an X-linked



metabolic disease. These patients will have hyperuricemia and should be

treated with allopurinol. These patients are also mentally retarded.

Nucleoside diphosphate kinase Nucleoside diphosphate kinase is involved in nucleotide synthesis

specifically, the conversion of nucleoside diphosphates to nucleoside

triphosphates, and vice versa.

Purine nucleoside phosphorylase Purine nucleoside phosphorylase converts guanosine to guanine and

inosine to hypoxanthine in the formation of uric acid.

Xanthine oxidase Xanthine oxidase is used in the formation of uric acid. It oxidizes hypoxanthine to

xanthine and xanthine to uric acid.

Asbestos exposure This condition is typically found in shipyard workers from years ago. The disease

process is not normally acute and leads to the classic cancer mesothelioma.

Asthma exacerbation You would expect to see a lower oxygen saturation level, along with wheezing

or decreased air movement on exam.

Carbon monoxide poisoning Anyone who comes in with a 100% oxygen saturation and in severe

respiratory distress with a normal exam should be considered for CO poisoning.

This condition can result from inhalation of car exhaust or an old gas heater that

has just been started up on a cold night. The diagnostic test is the ABG, which

reveals carboxyhemoglobin. The treatment is oxygen, hyperbaric if available.

Carbon monoxide has a very high affinity for hemoglobin; once it binds, it causes

the other three sites in the hemoglobin to be less likely to bind oxygen.

Pneumonia This diagnosis is a possibility but is less likely if the patient is in this much distress and has

a 100% oxygen saturation.



Pulmonary embolism The oxygen saturation is too high, although the acute onset of the illness is in

line with this diagnosis. A blood gas would be useful in this setting, where you

would expect a low PaO2.

The G2 phase involves checking DNA for errors. This phase follows immediately the S phase, in which

DNA is made. This phase is involved in checking DNA for errors.

In the cell cycle, most cells spend the majority of time in mitosis.Cells typically spend the majority of

time in interphase.

Mitosis involves semiconservative replication, and DNA is typically circular. Mitosis does involve

semiconservative replication, in which daughter DNA is partnered with parental

DNA. DNA is typically not circular.

Most epithelial cells remain in the G0 phase. G0 is a phase that indicates a cell is no longer actively

dividing. Epithelial cells are actively dividing and are not in the G0 phase.

Reverse transcription plays a significant role in DNA replication. Reverse transcription plays a limited

role in cell replication. It is involved in replication of highly repetitive sequencesof DNA.

Antisocial personality disorder Patients with antisocial personality disorder avoid conforming to

societal norms and are not concerned with the welfare of other people, animals,

and objects.

Avoidant personality disorder Avoidant personality disorder is a cluster C personality disorder.

Patients with avoidant personality disorder feel inferior to others, avoid

interacting with others, and are sensitive to rejection.



Histrionic personality disorder Histrionic personality disorder is a cluster B personality disorder.

Patients with this personality disorder are theatrical and extroverted. They will

often try to sexually seduce others, but they avoid intimate relationships.

Narcissistic personality disorder Narcissistic personality disorder is a cluster B personality disorder.

Patients with narcissistic personality disorder believe that they are more

important than others and are insensitive to the needs of others.

Paranoid personality disorder Patients with paranoid personality disorder (a clusterA personality

disorder) are distrustful of other people and do not take responsibility for their

own problems.

17 and older A person has a good chance of attaining stage IV ethics by age 17 or older, at which

point right behavior is viewed as lawful behavior. Life is seen as sacred in terms

of its place in a categorical moral or religious order.

Change the antibiotic because it is unlikely to cover Streptococcus bovis Vancomycin and gentamicin

provide broad empiric coverage of all the likely organisms of infective

endocarditis: Streptococcus viridans and bovis, and Staphylococcus aureus and

epidermitis.

Consult GI to initiate a GI workup Streptococcus bovis is associated with a 50% risk of colonic

malignancy, making a GI workup mandatory.

Consult Infectious Disease for the unusual nature of the organism Streptococcus bovis is one of the

normal organisms for infective endocarditis. Blood cultures are positive in

approximately 90% of patients. Those for whom it is not positive often have an

unusual organism.

Consult Social Service because the patient is a likely drug abuser Right-sided endocarditis is usually

associated with IV drug use. Tricuspid, rather than mitral, regurgitation would

be expected.



No change is management is necessary at this time With such a strong association of S. bovis with

colonic malignancy, one would be remiss in not investigating it.

Anomalous insertion of odd-chain fatty acids into membrane lipids The patient is pale, which might

suggest anemia. The most consistent sign of B12 deficiency is loss of vibration

sense in the legs, which can extent to the trunk. Changes in mental status are

frequently observed and include irritability, confusion, suspiciousness, and

emotional instability. Lack of cobalamin leads to accumulation of methylmalonyl

CoA and propionyl CoA. Excess propionyl CoA leads to displacement of succinyl

CoA, which results in formation of anamolous odd-chain fatty acids in

membrane lipids.

Prescribe a trial of ativan Night terrors are nightmares that are not recalled.

Prescribe a trial of imiprimine Imiprimine is used for bedwetting.

Prescribe a trial of phenobarbital Phenobarbital lessens REM sleep.

Psychiatric referral for forgotten trauma Forgotten trauma does not usually present with isolated

nightmares that are never remembered upon waking and that usually occur

during the first half of the night. They can be familial. Ativan is a benzodiazepine

that lessens stage IV sleep. Night terrors occur during stage IV sleep, so

benzodiazepines are often helpful for night terrors.

Which hormone is responsible for insulin resistance in gestational diabetes mellitus?

hPL Human placental lactogen is believed to be the main culprit in the development of GDM in

pregnant women. This hormone, which is produced in the placenta, is important

for ensuring a constant nutrient supply to the fetus. It causes lipolysis and hence

increases free fatty acids. It also has diabetogenic effects on the mother and

leads to increased levels of insulin and development of diabetes.



hCG is not believed to play a role in the development of GDM.

Estrogen Estrogen is not believed to play a role in the development of GDM.

LH Luteinizing hormone is not believed to play a role in the development of GDM.

Progesterone Progesterone is not believed to play a role in the development of GDM.

He complains of a circular, red, itchy patch of skin on his right forearm.

This is a dermatophyte infection of a microsporum species. Certain microsporum species, when hairs

are involved, will fluoresce under a Wood's lamp. Microsporum species infect

only hair and skin.

This is a dermatophyte infection of the epidermophyton species. Epidermophyton species do not

fluoresce under a Wood's lamp. E . floccosum infects skin and nails, but not hair.

Further examination of this area is warranted to narrow down the fungal species infecting the

individual. Of the species that cause dermatophyte infections, only microsporum

will fluoresce under a Wood's lamp.

This is a dermatophyte infection of a trichophyton species. Lyme disease is caused by Borrelia

bergdorferi, which is transmitted by a tick bite.

This is an erythema migrans rash of Lyme disease. The erythema migrans rash, which is usually

described as a bulls-eye' rash, does not fluoresce under a Wood's lamp. It is the

hallmark rash of Lyme disease. Lyme disease is caused by infection with Borrelia

bergdorferi, which is transmitted by a tick bite.

Epidural hemorrhage An epidural hemorrhage may follow a blow to the head. It usually presents with

a brief loss of consciousness, followed by a lucid interval that may last several

hours, followed by drowsiness and coma. Bleeding is usually from a torn artery,

most commonly the middle meningeal artery.

Intracerebral hemorrhage Intracerebral hemorrhages are most commonly seen in patients with

hypertension. They may produce a paralytic stroke.



Subhyaloid hemorrhage A subhyaloid hemorrhage is a hemorrhage in the eye between the retina and

vitreous body. It may be seen in conjunction with a subarachnoid hemorrhage.

Subarachnoid hemorrhage A subarachnoid hemorrhage most commonly occurs as the result of an

aneurysm of an intracranial artery. It results in signs of meningeal irritation,

such as severe headache, stiff neck, and loss of consciousness. There is no lucid

interval.

Subdural hemorrhage This injury typically follows a blow to the head that forcefully moves the brain

inside the skull. It is seen most commonly in the elderly population secondary to

shrinkage of the brain. There is no lucid interval.

Common hepatic artery The common hepatic artery runs along the upper edge of the pancreas before

dividing into the proper hepatic artery and gastroduodenal artery. It is not found

near the cystohepatic triangle.

Cystic artery The cystic artery travels through the cystohepatic triangle and is the most likely artery to

be injured during a cholecystectomy.

Left hepatic artery The left hepatic artery supplies the left portion of the liver. It is not located near

the cystohepatic triangle

Right gastric artery The right gastric artery supplies the stomach and is not likely to be injured during

a cholecystectomy.

Right hepatic artery The right hepatic artery supplies the right side of the liver and gives rise to the

cystic artery, which lies in the cystohepatic triangle. While it may be injured

during a gallbladder surgery, it is not the most common artery damaged during

dissection of that area.



P. falciparum The most feared form, it causes malignant malaria, which can manifest as cerebral

malaria. Cerebral malaria can lead to coma and is associated with a mortality

rate in excess of 20%.

P. malariae This organism causes benign quartan malaria. When chronic, P. malariae infection is also

associated with nephrotic syndrome due to glomerulonephritis.

P. ovale This organism causes benign tertian malaria. One important consideration with this parasite

is that hypnozoite forms can be present in the liver, causing relapse. For this

reason, primaquine must be added to the therapy.

P. simiovale This strain infects simian species. The four human malarial species are P. falciparum,

P. ovale, P. vivax , and P. malariae.

P. vivax This organism causes benign tertian malaria. One important consideration with this parasite

is that hypnozoite forms can be present in the liver, causing relapse. For this

reason, primaquine must be added to the therapy. In addition, P. vivax can be

associated with delayed splenic rupture.

Routine lab work shows an elevated bilirubin level of 2.3 mg/dL (normal = 0.21.0 mg/dL).

Gilbert's syndrome Gilbert's syndrome is often found by the presence of an elevated bilirubin level on

routine lab work in an otherwise asymptomatic individual. The bilirubin level

fluctuates, and may be elevated by stress, exercise, infection, or fasting. Patients

may notice scleral icterus or mild jaundice of the skin during these periods.

Gilbert's syndrome affects 3% to 7% of the population and is more common in

males than in females. The hyperbilirubinemia is caused by reduced hepatic

glucuronyl transferase activity.

Cirrhosis This patient has no risk factors for cirrhosis, including no reports of excessive alcohol use, no

hepatosplenomegaly, and normal liver function tests.



CriglerNajjar syndrome type I In CriglerNajjar Syndrome type I, the patient has no glucuronyl

transferase, kernicterus, and early death.

CriglerNajjar syndrome type II In CriglerNajjar syndrome type II, the patient has low levels of

glucoronyl transferase. Patients are usually diagnosed early in life, with severe

jaundice and a bilirubin level of 917 mg/dL.

Hemolytic anemia Hemolytic anemia is characterized by an elevated bilirubin level; however, the

complete blood count would reveal decreased hemoglobin and hematocrit

levels. The patient would also have an elevated reticulocyte count.

Decreased calcium, increased phosphate, normal alkaline phosphataseA patient with decreased

calcium, increased phosphate, and normal alkaline phosphatase would most

likely present with renal insufficiency.

Normal calcium, normal phosphate, increased alkaline phosphataseA patient with normal calcium,

normal phosphate, and increased alkaline phosphatase would not suggest

osteoporosis.

Increased calcium, decreased phosphate, increased alkaline phosphataseA patient with increased

calcium, decreased phosphate, and increased alkaline phosphatase would not

have osteoporosis but could be a candidate for hyperparathyroidism.

Increased calcium, increased phosphate, normal alkaline phosphataseThese lab results would not

suggest osteoporosis but could suggest vitamin D intoxication.

Normal calcium, normal phosphate, normal alkaline phosphatase This patient most likely has

osteoporosis; therefore, her calcium, phosphate, and alkaline phosphatase

would most likely be normal.

For which of the following cases is confidentiality allowed to be broken?



A patient is confides in you her plan for killing another person A person with a plan to harm another

person needs to be taken seriously. If there is no other way to warn the person

at risk, it is the obligation of anyone who knows of this plan to break

confidentiality.

A husband calls your office for his wife's test results without having her explicit permission to give outany information This scenario does not meet the requirements for breach of

confidentiality.

A parent asks you whether her teenage daughter has been taking birth control pills In most states,

teenagers are granted confidentiality from their parents regarding sexual

matters.

The local TV station contacts the emergency room to verify whether a celebrity has been recently

treated All patients, including celebrities, have the right to privacy and not to

have their presence confirmed or denied unless they authorize it.

Lysosomal storage Diseases such as Gaucher disease do not give the clinical findings described here.

An alpha-1,6-glucosidase deficiency In Cori's disease, patients lack a debranching enzyme.

A glucose-6-phosphatase deficiency In Von Gierke's disease, patients exhibit severe fasting

hypoglycemia and have increased amounts of liver glycogen.

A glycogen phosphorylase enzyme deficiency In McArdle's disease, patients exhibit cramps and

weakness after minimal exertion.

A lysosomal glucosidase deficiency In Pompe's disease, patients often die within the first year because

of a defective pump.

Which of the following hormones is responsible for stimulating pancreatic enzyme secretion,

stimulating gallbladder contraction, and inhibiting gastric acid secretion?



Cholecystokinin Cholecystokinin is responsible for these activities. It is stimulated by amino acids and

fatty acids.

Gastrin Gastrin stimulates gastric motility and the secretion of pepsinogen, hydrochloric acid, and

intrinsic factor.

Pepsin Pepsin is stimulated by acid and begins the process of protein digestion.

Secretin Secretin inhibits gastric acid secretion and stimulates bicarbonate secretion by the pancreas.

Somatostatin Somatostatin inhibits gallbladder contraction, pancreatic fluid secretion, small-bowel

fluid secretion, gastric acid secretion, and pepsinogen secretion. It is responsible

for the release of glucagons and insulin.

Antisocial personality disorder Antisocial personality disorder is a cluster A personality disorder.

Patients with conduct disorder in childhood have an increased risk of developing

antisocial personality disorder. Patients with antisocial personality disorder will

avoid conforming to societal norms and are not concerned with the welfare of

other people, animals, and objects.

Avoidant personality disorder Avoidant personality disorder is a cluster C personality disorder.

Patients with avoidant personality disorder feel inferior to others, avoid

interacting with others, and are sensitive to rejection.

Histrionic personality disorder Histrionic personality disorder is a cluster B personality disorder.

Patients with this personality disorder are theatrical and extroverted. They will

often try to sexually seduce others, but they avoid intimate relationships.

Narcissistic personality disorder Narcissistic personality disorder is a cluster B personality disorder.

Patients with narcissistic personality disorder believe that they are more

important than others and are insensitive to the needs of others.



Paranoid personality disorder Patients with paranoid personality disorder (a clusterA personality

disorder) are distrustful of other people and do not take responsibility for their

own problems.

Group B streptococci, E . coli, and Listeria Group B streptococci, E . coli, and Listeria are the common

causes of meningitis in newborns.

Listeria and E . coli While Listeria and E . coli are common causes of meningitis in the newborn, answer

A is correct because it includes Group B streptococci, a common cause of

meningitis in newborns.

N. meningitidis and H. influenzae B N . meningitidis and H. influenzae B are common causes of

meningitis in children, but not newborns. The incidence of infection with

H. influenzae B is decreasing due to the widespread use of the prevnar vaccine

against this pathogen.

S. pneumoniae and gram-negative rods S. pneumoniae is an uncommon cause of meningitis in

newborns, but it is a common cause of meningitis in children and adults. Gram-

negative rods are a common cause of meningitis in the elderly.

Staphylococcus aureus and Klebsiella pneumoniae Staphylococcus aureus and K lebsiella pneumoniae

are rare causes of meningitis.

Decreased number of CD4 count and increased p24 antigen One month after infection with HIV,

patients will have decreased levels of CD4 lymphocytes; this level eventually

increases two to three months after infection. One month after infection, p24antigen levels peak and then decrease by two months post-infection.

Increased anti-gp120 antigenAnti-gp120 antigen does not appear until 6 weeks after infection and

peaks around 812 weeks post-infection.



Increased anti-p24 antigen Anti-p24 antigen does not appear until 6 weeks after infection and peaks

Normal CD4 count and increased p24 antigen One month after infection with

HIV, patients will have decreased levels of CD4 lymphocytes; this level

eventually increases two to three months after infection. around 812 weekspost-infection

Normal CD4 count and increased p24 antigen One month after infection with HIV, patients will have

decreased levels of CD4 lymphocytes; this level eventually increases two to

three months after infection. One month after infection, p24 antigen levels peak

and then decrease by two months post-infection.

Normal CD4 count and undetectable p24 antigen One month after infection with HIV, patients will

have decreased levels of CD4 lymphocytes; this level eventually increases two to

three months after infection. One month after infection, p24 antigen levels peak

and then decrease by two months post-infection.

The husband suffers from a kinesin deficiency The deficiency is in the dynein protein

The patient suffers from Kartagener's syndrome The constellation of infertility,

bronchiectasis/sinusitis, and situs inversus should make you think of

Kartagener's syndrome. These patients suffer from a deficiency of the dynein

protein found in cilia that is responsible for ciliary motion. In the absence of thiscritical protein, males are infertile secondary to sperm immobility. The lack of

proper ciliary motility also means decreased bacterial clearance from the lungs

and sinuses, resulting in bronchiectasis and chronic sinusitis. The situs inversus is

secondary to improper cell mobility during embryogenesis.

Flutamide The patient has metastatic carcinoma of the prostrate. He has a history of BPH, which is

common in men older than 50 years of age. Superimposed on the BPH the

patient has developed prostate cancer that has now metastasized to his spine

not an uncommon mode of presentation for prostate cancer. Flutamide is an

oral anti-androgen at the level of the prostate gland and prostate cancer cells. It

blocks the stimulation signal for proliferation in these cells and controls the rate

of cell replication.



Actinomycin D This drug binds to double-stranded DNA and inhibits DNA-directed RNA synthesis. It is

not indicated for prostate cancer.

Carboplatin This drug binds to DNA and creates interstrand cross links. It is not indicated for prostate

cancer.

Interferon-alpha, -beta, or -gamma Interferons are not indicated for prostate cancer.

Mitomysin C This alkylating drug is not indicated for prostate cancer.

A 24-year-old male is thrown from a car that he drove into a tree. He suffers from a T6 spinal crush

injury. After he recovers from his acute injury, what is the most appropriate

course of action regarding his bladder?

The bladder should remain catherized until the patient's micturation reflexes return. The patient can

then be taught to cutaneously stimulate the genital area to stimulate a

micturation reflex. In this case, spinal shock causes complete suppression of the

micturation reflex for the first few days.

The patient will have frequent bladder reflux with resulting bladder infections. Bladder dyssynergia can

be caused by upper spinal cord lesions, which causes ureteral reflux.

The bladder is paralyzed, and the patient will have to use abdominal compression and straining to void.

Bladder paralysis will be caused by lesions below T12. Abdominal straining and

compression, called Crede's maneuver, will often allow voiding.

The patient will have a bladder that fills and dribbles urine continually. Lesions that affect the sensory

nerves prevent normal micturation reflex. The bladder will fill to capacity and

overflow a little at a time.



The patient should be taught how to self-catherize, because he will never be able to control his

bladder. Self-catherization is appropriate if the patient can never control his

bladder. This permanent condition can be caused by loss of sensory nerves.

Codeine This drug is a narcotic. Narcotics have an addictive potential.

Heroin This drug is a narcotic. Narcotics have an addictive potential.

Hydrocodone This drug is a narcotic. Narcotics have an addictive potential.

Morphine This drug is a narcotic. Narcotics have an addictive potential.

Tramadol This agent is the only non-narcotic drug on the list. A patient with a history of substance

abuse (no matter what the substance of abuse was) must not be given

medications that have the potential to be addicting and abused. The diagnosis

of substance abuse is a lifetime diagnosis. Patients so diagnosed, even if their

addiction resolves, continue to maintain that diagnosis for life.

A 25-year-old female has recently had her first psychotic break. After many months of therapy, she has

been diagnosed with paranoid schizophrenia. She has been responding well to her

inpatient olanzapine regimen, and you would like to continue this medication with

her while following her in the outpatient setting. Which of the following features

of her family history would be of the greatest concern to you?

Three first-degree relatives with type II diabetes mellitusThere is an established genetic component to

type II diabetes mellitus. Olanzapine has been shown to cause significant

increases in weight, which in turn promotes a state of hyperinsulinemia and

insulin resistance. It would be worrisome to start a patient with a significant

family history of diabetes mellitus on a medication that would further increase

her risk of developing this disease via weight gain and insulin resistance.

A 65-year-old woman comes into your office complaining of a left-sided headache, jaw pain, and stiff,

achy shoulders for about one week. She has no other medical problems and has

never had a headache before this presentation. On examination, she has a

prominent, pulsating left temporal artery that is very tender to palpation. Yoususpect temporal arteritis (giant-cell arteritis) and decide to do a biopsy to

confirm the diagnosis. What is the best course of action in the meantime, while

waiting for the results?

High-dose prednisone A serious consequence of untreated temporal arteritis is blindness due to

inflammation extending to the optic nerve. If your clinical suspicion is high, it is



best to start steroids immediately. If the biopsy is negative for temporal

arteritis, the short course of steroids is unlikely to have any adverse effects.

Tylenol for headache relief Although Tylenol can help relieve pain symptoms and could be given as an

adjuvant to treatment, it is also important to start the patient on steroids.

Nothing; wait for results before giving any treatment Any delay in treatment while waiting for the

results increases the patient's risk of blindness.

Antibiotics Temporal arteritis is not an infectious process, but rather is caused by chronic

inflammation of large blood vessels. Antibiotics would not help reduce the

inflammation.

Have other family members come in for evaluation Temporal arteritis is not a hereditary process.

However, its incidence increases with advancing age. If family members present

with similar complaints, it is best to have them evaluated.

During a busy day in the emergency room, a 37-year-old male presents complaining of acute epigastric

abdominal pain, describing it as shooting straight through to my back. He alsostates that he has not been able to eat because of nausea and vomiting. On

examination, the patient is afebrile and uncomfortable, and he requests

medication for his pain. He appears intoxicated. The abdominal exam reveals mild

distention, absent bowel sounds, and extreme pain on palpation, but no rebound

tenderness. Initial lab results show elevated amylase and lipase levels. A KUB

shows multiple calcifications in the abdomen. Which diagnosis best explains these

results?

Pancreatitis In the setting of alcohol use, this patient's presentation is convincing for acute

pancreatitis in the context of chronic pancreatitis.A

lcohol use and gallstones arethe main causes of acute pancreatitis in the United States; the presence of

pancreatic calcifications suggests that the patient has experienced previous

episodes.A follow-up CT scan or ultrasound may reveal pancreatic fluid

collections, indicating the development of a pseudocyst.



Aortic dissection Patients with aortic dissection classically complain of intense epigastric pain that

radiates to the back, but do not have elevated lipase and amylase levels.

Appendicitis This patient presents with acute, fixed, and intense epigastric pain. Appendicitis typically

begins as colicky central abdominal pain that worsens as it localizes to the right-

lower quadrant. It is not generally associated with elevated lipase levels.

Esophagitis Erosive conditions of the esophagus are not associated with elevated amylase and lipase

levels.

Gastritis Although patients with gastritis often present with epigastric pain and nausea, serum

amylase and lipase levels are not typically elevated. In addition, abdominal

calcifications in this setting are strongly suggestive of pancreatic calcifications,

indicating that the patient likely has a chronic condition.

As an intern in the ER, you evaluate a 55-year-old patient with a history of a duodenal ulcer who

complains of severe, nonremitting, mid-epigastric pain and vomiting of bright red

blood. An upright X ray reveals free air under the diaphragm, and you suspect a

perforated ulcer. Endoscopy confirms your suspicion and reveals a perforated

ulcer in the posterior portion of the first part of the duodenum. Perforation into

which artery best explains this patient's symptoms?

Gastroduodenal artery This artery descends immediately behind the first part of the duodenum;

ulcers commonly penetrate into this vessel. It arises from the common hepatic

artery and gives off the right gastroepiploic and superior pancreaticoduodenal

arteries.

Cystic artery This artery does not run near the first portion of the duodenum.

Hepatic artery The right and left hepatic arteries are branches of the proper hepatic artery, which is

itself a branch of the common hepatic artery. These arteries are closer to the

liver and the second portion of the duodenum.



Right gastric artery This artery runs along the lesser curvature of the stomach away from the

duodenum.

Right gastroepiploic artery This artery runs along the greater curvature of the stomach.

According to current thinking, which of the following is the first-line treatment for congestive heart

failure?

ACE inhibitors ACE inhibitors decrease vascular resistance, decrease blood pressure, and increase

cardiac output. They also blunt the release of aldosterone and epinephrine

caused by angiotensin II. Studies have shown that ACE inhibitors reduce the

chances of arrhythmic death, MI, and stroke. Interestingly, studies scheduled to

be published in the near future may make new statements about ACE inhibitors

and beta blockers, so this answer may change in the future. Currently, however,

ACE inhibition is the correct answer for this question.

Beta blockers Once thought to be contraindicated in CHF, these medicines are now finding a place in

the treatment of CHF and the prevention of further disease and complication.

They are not the first-line option, however.

Digitalis Widely used in heart failure, digitalis has no effect on mortality and is not used as a first-line

therapy. Its utility actually derives from its ability to decrease the number of

hospitalizations of patients with CHF.

Diuretics While useful in heart failure because of its ability to reduce the effects of volume overload

and decrease the symptoms of paroxysmal nocturnal dyspnea and orthopnea,

diuretics are is not the first-line option for CHF.

Macrolides This class of drugs, and all classes of antibiotics, have not been shown to offer any

benefits in the treatment of CHF.



A 25-year-old woman with regular menses is given an estrogen challenge. The challenge consists of

exogenous estrogen supplementation to see if her LH level will increase. Which of

the following regimens would be most effective?

Estrogen 10 days after menses High levels of estrogen are needed to stimulate adequate LH

production.

Estradiol 20 days after menses If estradiol was given 20 days after menses, then the cycle would

already be in the luteal phase. Once in the luteal phase, the LH level will not rise

until the next cycle.

Progesterone 10 days after onset of menses Progesterone level is typically very low during the

follicular phase. This hormone does not stimulate LH production.

Progesterone 20 days after onset of menses Progesterone does not stimulate LH production.

Synthetic FSH 15 days after onset of menses FSH is the not the principal stimulator of LH production.

A 47-year-old African American male presents for follow-up for depression. He denies improvement

after eight weeks of sertraline with good compliance. His smoking has increased

to three packs per day, up from two packs per day for 30 years. He admits tointermittent back pain, incapacitating pruritus, and a 30-pound weight loss.

Umbilical tenderness and a distended gallbladder are noted on physical

examination. Which of the following is the most likely to be true in this case?

The pancreatic head is the origination site of the patient's pancreatic carcinoma. Pancreatic carcinoma

most often occurs in the pancreatic head. This location allows earlier

identification as compared to the tail of the pancreas. However, surgical

procedures require removal of the pancreatic head, gallbladder, and a portion of

the duodenum (Whipple procedure). Migrating thrombophlebitis is often

observed with pancreatic carcinoma.

No association has been made between cigarette smoking and pancreatic carcinoma. Smoking

increases the risk of pancreatic carcinoma.



The patient's tumor represents the malignant transformation of exocrine cells. Duct cells represent 4%

of the healthy pancreas, but 99% of primary pancreatic malignancies originate

from duct cell neoplasia.

The patient's gallbladder distention is due to choledocholelithiasis from elevated cholesterol

nucleation. Courvoisier's sign notes the tendency of biliary-tractrelated

malignancies to lead to gallbladder distention, but cholelithiasis-related disease

results in a normal- or reduced-size gallbladder.

Lifespan has been improved to greater than 10 years with current chemotherapy regimens.The

prognosis for pancreatic carcinoma remains poor, with death typically occurring

within one year of diagnosis.

A four-year-old white female presents to the pediatric clinic for follow-up due to developmental delay.

Her medical history reports frequent episodes of otitis media, bronchitis, and

pneumonia. Physical examination reveals coarse facial features, gingival

hypertrophy, joint stiffness, claw hand deformity, and generalized hypotonia.

Significant motor delay is appreciated. Electron microscopy of muscle biopsy

demonstrates numerous intracytoplasmic inclusions, which are membrane-bound

vacuoles filled with fibrillogranular material. I-cell disease is suspected. What is

the function of the deficient enzyme?

Phosphorylation of mannose residues Failure to phosphorylate mannose residues targets intracellular

enzymes to extracellular sites. Lysosomal enzymes cannot be routed

appropriately, and enzymes accumulate in the plasma. Lysosomal substrates

accumulate, as the lytic enzymes are not present intracellularly. Key findings are

gingival hypertrophy and hypotonia. Death is common before the patient

reaches age eight years.

Breakdown of dermatan sulfate and heparan sulfate Mucopolysaccharidoses and another class of

lysosomal disorders, Hurler's syndrome, Hunter's syndrome, Scheie's syndrome,

and Sanfilippo's syndrome are all disorders due to faulty metabolism of

dermatan sulfate and heparan sulfate. Hurler's syndrome and Scheie's syndrome

are notable for corneal clouding. Scheie's syndrome is the only listed disorder

with normal intellect and life expectancy. Hunter's syndrome is X-linked, where

the remaining disorders are autosomal recessive.



Cleavage of disaccharides Brush border enzymes include lactase and isomaltase sucrase. These

disorders cause flatulence due to bacterial digestion of disaccharides and

osmotic diarrhea.

Cleavage of fructose Fructose intolerance is caused by lack of aldolase B. Phosphorylated fructose

accumulates within the cell due to insufficient metabolism. Possible sequelae

include hypoglycemia, hemorrhage, and liver failure. Avoidance of fructose and

sucrose is curative.

Degradation of sphingolipids Lysosomal hydrolytic enzymes are missing in this class of enzyme

deficiencies. Sphingolipidoses include Tay-Sachs disease, Meimann-Pick disease,

and Fabry's disease. Lysosomal accumulation of sphingolipids often leads to

mental retardation and shortened life expectancy.

Metabolism of galactose Galactosemia, as caused by uridyltransferase or galactokinase deficiency,

may lead to adverse effects that include cataract formation and mental

retardation. Accumulation of galactitol damages nerve tissue, liver, kidney, and

the lens of the eye. Strict avoidance of galactose and lactose is required.

Which of the following antibiotics works by blocking cell-wall synthesis through the inhibition of

peptidoglycan cross-linking?

Penicillin Along with the cephalosporins, imipenem and actreonam, penicillin inhibits peptidoglycan

cross-linking.

Aminoglycosides Block protein synthesis at the 30S ribosomal subunit, as do the tetracyclines.

Chloramphenicol Blocks protein synthesis at the 50S ribosomal subunit.

Clindamycin Blocks protein synthesis at the 50S ribosomal subunit.

Macrolides Block protein synthesis at the 50S ribosomal subunit.

Quinolones Block DNA topoisomerases.

Rifampin Blocks mRNA synthesis.



Sulfonamides Block nucleotide synthesis.

Vancomycin Blocks peptidoglycan synthesis.

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USMLE step 1 important points