USMLE Step 1 High Yield Summary a Crunch Time Cram

USMLE Step 1 High Yield Summary


A Crunch Time Cram The following pages contain high yield information designed for review in the days just

preceding the Step 1 examination.

MOST COMMON

Often on the USMLE exam, the student finds two responses that could potentially answer a

question. The NBME is testing the student to identify the more common of the two responses;

for example, the more common cause, site, or type. Below is a high yield summary of the most

common characteristics of the various disorders listed in this text.

Nervous System

Most Common…

Aneurysm of Circle of

Willis

Anterior communicating artery; bitemporal hemianopsia

Blindness Diabetic retinopathy

Blindness—preventable Chlamydia trachomatis

Bacterial meningitis—

elderly Streptococcus pneumoniae


newborns E. coli


toddlers

Haemophilus influenza type b


young adults Neisseria meningitidis

Cancer of the brain—child Medulloblastoma (cerebellum)

Cancer of the brain—adult Astrocytoma (including glioblastoma multiforme), then

metastasis, meningioma, schwannoma

Dementia 1. Alzheimer's 2. Multi-infarct dementia

Demyelinating disease Multiple sclerosis

Location of adult brain

tumors Above tentorium

Location of childhood

brain tumors

Below tentorium (Mnemonic: Children are short, they cannot reach

above the tentorium)

Mental retardation 1. Down syndrome or Fragile X 2. Fetal alcohol syndrome

Motor neuron disease Amyotrophic lateral sclerosis (ALS)

Viral encephalitis HSV


Cardiovascular System

Most Common…

Acute mitral insufficiency—children Kawasaki disease

Aneurysm Abdominal aorta

AV fistula Penetrating knife wound

Cancer of the heart—adults Metastases

Cancer of the heart—primary—adults Myxoma “Ball Valve”

Cancer of the heart—primary—kids Rhabdomyoma

Cardiomyopathy Dilated (congestive) cardiomyopathy

Cause of acute endocarditis Staphylococcus aureus

Cause of subacute endocarditis Streptococcus viridans

Congenital cardiac anomaly Ventricular septal defect (membranous >

muscular)

Congenital early cyanosis Tetralogy of Fallot

Coronary artery thrombosis Left anterior descending

Death in HTN 1. Acute mitral insufficiency 2. Lenticulostriate stroke

3. Renal failure (benign nephrosclerosis)

Death in the United States Ischemic heart disease

Heart murmur Mitral valve prolapsed

Heart valve in bacterial endocarditis Mitral

Heart valve in bacterial endocarditis in IV drug

users

Tricuspid

Heart valve involved in rheumatic fever Mitral > Aortic

Hypertension 1. Essential (95%)

2. Renal disease

Hypertension—children Renal disease; cystic disease, Wilms tumor

Hypertension—young women Oral contraceptives

Myocarditis Coxsackie B virus

Right heart failure Left heart failure

Secondary hypertension Renal disease

Sites of atherosclerosis Abdominal aorta > coronary > popliteal >

carotid

Vasculitis (of medium and small arteries) Temporal arteritis

Respiratory System

Most Common…

Cause of pneumonia in debilitated,

hospitalized patient

Klebsiella

Cause of epiglottitis Haemophilus influenza type b

Cause of IV drug user

bacteremia/pneumonia Staphylococcus aureus


Cause of opportunistic infection of

AIDS Pneumocystis carinii is most common overall

Death in Alzheimer patients Pneumonia

Fatal genetic defect in Caucasians Cystic fibrosis

Pneumonia—community—typical 1. Streptococcus pneumoniae

2. H. influenza

3. Klebsiella

Pneumonia—hospital acquired 1. Klebsiella

2. Pseudomonas

3. E. coli

Pneumonia—community—atypical 1. Mycoplasma 2. Legionella

Pulmonary HTN COPD

SIADH Small cell carcinoma of the lung

Tracheoesophageal fistula Lower esophagus communicates with trachea, upper

esophagus ends in blind pouch

Gastrointestinal System

Most Common…

Bug in food poisoning Staphylococcus aureus

Bug in GI tract 1. Bacteroides 2. E. coli

Cancer of the appendix Carcinoid—rarely metastasizes

Cancer of the esophagus Leiomyoma

Cancer of the esophagus—

malignant

Squamous cell carcinoma (60%) > adenocarcinoma (40%)

Cancer of the liver Metastasis; lung > GI

Cancer of the liver—primary,

benign

Cavernous hemangioma

Cancer of the liver—primary Hepatocellular carcinoma

Cancer of the mouth Squamous cell carcinoma or mucoepidermoid

carcinoma

Cancer of the mouth—upper lip Basal cell carcinoma

Cancer of the nasal cavities Squamous cell carcinoma

Cancer of the pancreas Adenocarcinoma (usually in the head of pancreas)

Cancer of the salivary glands Pleomorphic adenoma

Cancer of the small bowel Carcinoid—frequent metastasis from ileum

Cancer of the spleen—benign Cavernous hemangioma


Cancer of the stomach Gastric adenocarcinoma (intestinal type or diffuse type)

Cirrhosis Alcohol

Congenital GI anomaly Meckel diverticulum

Diarrhea—children Rotavirus

Dietary deficiency Iron

GI obstruction 1. Adhesions 2. Indirect inguinal hernia

Intussusception Terminal ileum into cecum

Liver disease Alcoholic liver disease

Liver infection Viral hepatitis—HVA

Lysosomal storage disease Gaucher disease

Portal hypertension Cirrhosis

Protozoal diarrhea Giardia

Site of diverticula Sigmoid colon

Surgical emergency Acute appendicitis

Worm infection in the United States 1. Pinworm 2. Ascaris

Renal System

Most Common…

Amyloidosis Immunologic (Bence Jones protein in multiple myeloma is also called

the amyloid light chain)

Death in SLE patients Lupus nephropathy type IV (diffuse proliferative)

End-stage renal disease Diabetes

Glomerulonephritis IgA nephropathy (aka Berger's)

Nephrotic syndrome—

adults

Membranous glomerulonephritis

Nephrotic syndrome—

kids Minimal change disease

Renal failure Acute tubular necrosis

Endocrine System

Most Common…

Addison disease 1. Autoimmune 2. Infection

Cancer of the adrenal medulla—

adults Pheochromocytoma

Cancer of the adrenal medulla—kids Neuroblastoma

Cancer of the pituitary 1. Prolactinoma 2. Somatotropic “acidophilic” adenoma

Cancer of the thyroid Papillary carcinoma

Congenital adrenal hyperplasia 1. 21-Hydroxylase deficiency 2. 11-hydroxylase deficiency


Cushing's 1. Exogenous steroid therapy 2. Primary ACTH tumor

3. Adrenal adenoma

4. Ectopic ACTH tumor

Enzyme deficiency 21 hydroxylase—95% of congenital adrenal

hyperplasia

Hypercalcemia Hyperparathyroidism

Hyperparathyroidism—primary 1. Solitary adenomas 2. Parathyroid hyperplasia

3. Parathyroid carcinoma

Hyperparathyroidism—secondary Hypocalcemia due to chronic renal failure

Hyperthyroidism Graves disease

Hypopituitarism—adults Nonfunctioning pituitary adenoma

Hypopituitarism—kids Craniopharyngioma

Hypothyroidism Hashimoto thyroiditis

Peripheral neuropathy Diabetes mellitus

Thyroid disease Goiter

Reproductive System

Most Common…

Breast mass (premenopausal) Fibrocystic change (premenopausal)

Breast mass (postmenopausal) Breast carcinoma

Cancer in gynecologic—malignancy Endometrial carcinoma

Cancer in men Prostate carcinoma

Cancer in women Leiomyoma (fibroids)

Cancer in women—malignant Breast carcinoma

Cancer of the breast Infiltrating ductal adenocarcinoma

Cancer of the ovary—benign Serous cystadenoma

Cancer of the ovary—malignant Serous cystadenocarcinoma

Cancer of the placenta—benign Cavernous hemangioma

Cancer of the testicles Seminoma

Cancer that invades the female GU tract Endometrial adenocarcinoma

Cause of PID Neisseria gonorrhoeae or Chlamydia

Chromosomal disorder Down syndrome

Hernia Indirect

Opportunistic infection in AIDS Pneumocystis carinii

Sexually transmitted disease Chlamydia

Musculoskeletal System


Most Common…

Bacterial arthritis in young Adults N. gonorrhea

Cancer of the bone Metastases from breast and prostate

Cancer of the bone—primary—adults Multiple myeloma

Cancer of the connective tissue—benign Lipoma

Cancer of the skin Basal cell carcinoma

Carpal bone dislocation Lunate

Carpal bone fx Scaphoid

Disk herniation L4-L5

The Hematopoietic and Lymphoreticular System

Most Common…

Cancer—leukemia—14 y old ALL

Cancer—leukemia—60 y old CLL

Cancer—leukemia—15-39 y

old AML

Cancer—leukemia—40-60 y

old CML

Cancer in infancy Hemangioma

Cancer in children 1. Leukemia

2. Medulloblastoma of cerebellum

Cancer; malignant lymphoma

in children Burkitt lymphoma

Cancer; site of metastasis Regional Iymph nodes

Cancer; site of metastasis (2nd

most common) Liver

Cancer; genetic alteration p53

Hereditary bleeding disorder von Willebrand Disease

Single gene disorder Thalassemia

Type of hodgkin lymphoma Mixed cellularity versus lymphocytic predominance,

lymphocytic depletion, and nodular sclerosis

Type of nonhodgkin

lymphoma Follicular, small cleaved


QUICK LISTS

The following Quick Lists contain high yield information organized by basic science subject.

Physiology

Quick List: Important Formulas

Formula Notes

Cardiac output CO = Rate of O2 Consumption/(Arterial O2

Content - Venous O2 Content)

CO = SV × HR

SV = Stroke volume

HR = Heart rate

Mean arterial

pressure

MAP = CO × TPR

MAP = 1/3 SBP + 2/3 DBP

CO = Cardiac output

TPR = Total peripheral

resistance

SBP = Systolic blood pressure

DBP = Diastolic blood

pressure

Stroke volume EDV - ESV EDV = End diastolic volume

ESV = End systolic volume

Ejection fraction SV/EDV × 100 SV = Stroke volume

EDV = End diastolic volume

Resistance 8ηL/πr4 η= Viscosity

L = length

r = radius

Net filtration

pressure

(PC - PI) - (πC - πI) PC = Hydrostatic capillary

pressure

PI = Hydrostatic interstitial

pressure

πC = Osmotic capillary

pressure

πI = Osmotic interstitial

pressure


Glomerular

filtration rate

GFR = Kf (PGC - PBS) - (πGC - πBS)

GFR = Cinulin = Uinulin × V/Pinulin

Kf = filtration constant

PGC = Hydrostatic pressure in

glomerular capillaries

PBS = Hydrostatic pressure in

Bowman's space

πGC = Osmotic pressure in

glomerular capillaries

πBS = Osmotic pressure in

Bowman's space

Cinulin = Clearance of PAH

Uinulin = Urine concentration of

PAH

V = Urine flow rate

Pinulin = Plasma concentration

of PAH

Effective renal

plasma flow

CPAH = UPAH × V/PPAH CPAH = Clearance of PAH

UPAH = Urine concentration of

PAH

V = Urine flow rate

PPAH = Plasma concentration

of PAH

Renal blood flow RPF/(1-Hct) RPF = Renal plasma flow

Hct = Hematocrit

Filtration fraction GFR/RPF GFR = Glomerular filtration

rate

RPF = Renal plasma flow


Free water

clearance

CH2O = V - Cosm, where

Cosm = Uosm V/Posm

CH2O = Clearance of water

Uosm = Urine osmolarity

Posm = Plasma osmolarity

V = Urine flow rate

Biostatistics


Formula

Sensitivity TP/(TP + FN)

Specificity TN/(TN + FP)

Positive predictive value TP/(TP + FP)

Negative predictive value TN/(TN + FN)

Prevalence TP + FN/(TP + FP + TN + FN)

Generally calculated by incidence × duration of disease

Incidence Generally calculated by number of new cases/susceptible population

Relative risk RR = [TP/(TP + FP)]/[FN/(FN + TN)]

Attributable risk AR = [TP/(TP + FP)]-[FN/(FN + TN)]

Genetics

Quick List: Inherited diseases

Mode of

inheritance Diseases

Autosomal

dominant

diseases

Adult polycystic kidney disease, familial hypercholesterolemia, Marfan

syndrome, Neurofibromatosis type 1, Neurofibromatosis type 2, Tuberous

sclerosis, von Hippel—Lindau disease, Huntington disease, Familial

adenomatous polyposis, Hereditary spherocytosis, Achondroplasia

Autosomal

recessive

diseases

Cystic fibrosis, albinism, alpha1-antitrypsin deficiency, phenylketonuria,

thalassemias, sickle cell anemia, glycogen storage disease,

mucopolysaccharidoses (except Hunter disease), sphingolipidoses (except

Fabry disease), infant polycystic kidney disease, hemochromatosis

X-linked

dominant

diseases

Hypophosphatemic rickets

X-linked

recessive

diseases

Bruton's agammaglobulinemia, Wiskott-Aldrich syndrome, Fragile X

syndrome, G6PD deficiency, ocular albinism, Lesch-Nyhan syndrome,

Duchenne muscular dystrophy, Hemophilia A and B, Fabry disease, Hunter


syndrome

Mitochondrial

disease

Leber hereditary optic neuropathy, mitochondrial myopathies

Trisomies Down syndrome (Chromosome 21), Edward syndrome (Chromosome 18),

Patau syndrome (Chromosome 13)

Trinucleotide

repeat diseases

Huntington diease, myotonic dystrophy, Friedreich ataxia, fragile X syndrome

Pharmacology


Formula Notes

Volume of

distribution

Total drug in body/plasma concentration

Clearance Rate of elimination of drug/plasma

concentration

Half life 0.7 × Volume of distribution/Clearance

Loading dose Target plasma concentration × Volume of

distribution/Bioavailability

Bioavailability = 1, when

medication given IV

Maintenance

dose

Target plasma concentration ×

Clearance/Bioavailability

Bioavailability = 1, when

medication given IV

Quick List: Important Drug Side Effects based on Organ System (Figure 1)


FIGURE 1 Important drug side effects based on organ system


Quick List: Drugs to Avoid in Pregnancy

Drug Reason

Atorvastatin Congenital defects, termination of pregnancy

ACE inhibitors (captopril, enalapril, fosinopril,

lisinopril, and quinapril)

Fetal renal malformations

Aminoglycosides Ototoxicity

Chloramphenicol Gray baby syndrome

Erythromycin Acute cholestatic hepatitis (mother),

Embyrotoxic (clarithromycin)

Fluroquinolones Cartilage damage

Griseofulvin Teratogenic

Methysergide Oxytocic effects

Metronidazole Mutagenesis

Ribavirin Teratogenic

Sulfonamides Kernicterus

Tetracyclines Discolored teeth, inhibition of bone growth

Warfarin Teratogenic

Quick List: CYP-450 Interactions

Effect Agent Notes

Inhibitors Isoniazid, sulfonamides, cimetidine,

ketoconazole, erythromycin, grapefruit

juice

Inducers Quinidine, barbiturates, phenytoin,

rifampin, griseofulvin, carbamazepine,

St. John's wort

While induction is the more important effect,

quinidine can both induce and inhibit

different isoforms of CYP-450

Quick List: Antidotes

Toxic agent Treatment

Acetaminophen N-acetylcysteine

Amphetamine Ammonium chloride (acidify urine)

Anticholinesterases Atropine, pralidoxime

Anticholinergic Physostigmine salicylate

Antimuscarinic Physostigmine salicylate

Arsenic Dimercaprol (BAL), sucimer, Penicillamine

Benzodiazepines Flumazenil

Beta blockers Glucagon

Carbon monoxide 100% oxygen, hyperbaric oxygen

Copper Penicillamine

Cyanide Nitrite, hydroxocobalamin, thiosulfate

Digitalis Stop digoxin, normal potassium, lidocaine, anti-dig Fab fragments,

Mg2+


Ethylene glycol

(antifreeze)

Ethanol, dialysis, fomepizole

Gold Dimercaprol (BAL), sucimer, Penicillamine

Heparin Protamine

Iron Deferoxamine

Lead CaEDTA, dimercaprol, succimer, penicillamine

Mercury Dimercaprol (BAL), sucimer

Methemoglobin Methylene blue

Methanol Ethanol, dialysis, fomepizole

Opioids Naloxone/natrexone

Organophosphates Atropine, pralidoxime

Salicylate Sodium bicarbonate (alkalinize urine)

Streptokinase Aminocaproic acid

Tricyclic antidepressants Sodium bicarbonate (serum alkalinization)

tPA Aminocaptoic acid

Warfarin Vitamin K, fresh frozen plasma

Microbiology

Quick List: Buzzwords for Microbiological Infections

Clinical characteristics Organism

Branching rods in oral infections Actinomyces israeli

Chancroid Haemophilus ducreyi

Clue cells Gardenella vaginitis

Cold agglutinins Mycoplasma pneumoniae

Currant jelly sputum Klebsiella

Dog or cat bite Pasteurella multocida

Erythema chronicum migrans Lyme disease

Ghon focus Primary tuberculosis

Jarisch—Herxheimer reaction Syphillis—treatment of an asymptomatic patient results in

rapid lysis leading to symptoms

Negri bodies Rabies

Owl's eye CMV

Pediatric infection Haemophilus influenzae

Pneumonia in cystic fibrosis or

burn infections

Pseudomonas aeruginosa

Rash on palms or soles Rocky Mountain Spotted fever, Secondary syphillis

Roth spots in retina Endocarditis

Slapped cheeks Erythema infectiosum

Splinter hemorrhages in finger

nails

Endocarditis

Strawberry tongue Scarlet fever

Suboccipital lymphadenopathy Rubella


Sulfur granules Actinomyces israeli

Traumatic open wound Clostridium perfringens

Tabes dorsales Tertiary syphillis

Thumb sign on lateral X-ray Epiglottis (usually with Haemophilus influenzae)

Urethritis, conjunctivitis, arthritis Reiter syndrome

Quick List: Gram Stain Characteristics of Various Bacteria

Gram Stain

Characteristics Organisms

Gram positive cocci Staphylococcus (catalase +), Streptococcus (catalase -), Enterococcus

(catalase -)

Gram positive rods Clostridium (anaerobe), Corynebacterium, Listeria, Bacillius

Gram negative cocci Neisseria

Gram negative coccoid

rods

Haemophilus influenzae, Pasteurella, Brucella, Bordetella pertussis

Gram negative rods Lactose fermenters: Klebsiella (fast*), E. coli (fast), Enterobacter (fast),

Citrobacter (slow*), Serratia (slow)

Lactose nonfermenter: Shigella (oxidase -), Salmonella (oxidase -),

Proteus (oxidase -), Pseudomonas (oxidase +) *

Fast fermenter, Slow fermenter.

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USMLE Step 1 High Yield Summary a Crunch Time Cram