December Board Review

Renal: Part Deux

Test Question

• In the epic Christmas classic “National Lampoon’s Christmas Vacation,” what was the name of cousin Eddie’s dog?– A. Buff– B. Barf– C. Snot– D. Chewie

HYPERTENSION

Question #1

• A 12-year-old boy has the following vitals at his routine health supervision visit: HR 75 beats/min and BP 128/85 mmHg using the appropriate-sized cuff (>95% for height). His weight is above the 95th percentile and height is at the 50th percentile. The remainder of the physical exam is normal.

• Of the following, the MOST appropriate next step is:– A. BUN, Cr, electrolytes– B. Echocardiogrpahy– C. Repeat BP over 3 visits– D. Advise therapeutic lifestyle change– E. Repeat BP in 6 months

Diagnostic Evaluation

• COST• Confirm the diagnosis• Organize a diagnostic approach• Determine the Severity of the HTN• Treat the HTN effectively

Confirm Diagnosis

Ensure proper BP cuff size ( know that may be a cause of false readings)

-Bladder should encircle the arm by at least 80%

Question #2• A 15-year-old girl comes in for health supervision visit.

She has no complaints and is doing well in school. She is on the cross-country running team. She is not receiving any prescription medication. On PE she appears thin, but is otherwise normal. Her height and weight are at the 25%. Her HR is 100 beats/min and her BP is 145/95 mmHg.

• The MOST appropriate next step is:– A. BUN, Cr, electrolytes– B. Echocardiography– C. Recommend therapeutic lifestyle change– D. Review the list of OTC medications she has used– E. Screen for the use of anabolic steroids

Organize a Diagnostic Approach

• MONSTER– Medications– Obesity– Neonatal history– Symptoms or signs– Trends in the family– Endocrine or renal

•BMI > 95%•3 to 5 times more likely to have hypertension•Can have obstructive sleep apnea syndrome (OSAS)• Causes significantly higher diastolic BPs

Question #3

• A 11-year-old female comes in for a health supervision visit. She has no complaints. Her BP is 121/82 mmHg. Her height is at the 10% and weight is at the 95%. On physical exam she is obese with abdominal striae and has a rash on her face. Family history is negative.

• Of the following, the MOST likely cause of her HTN is:– A. Essential HTN– B. Cushing’s syndrome– C. Neurofibromatosis– D. Systemic lupus erythematous– E. Renal disease

Renal artery stenosis is assoc. with Williams syndrome

Suggested Eval for Children with HTN

Question #4

• A 17-year-old athlete well-known to your practice comes in complaining of headaches for the past 2 weeks. He has a history of asthma which is well-controlled. He denies using any illicit or prescription drugs. His BP is 180/120 mmHg. You repeat the measurement using a leg cuff of proper size and obtain the same result.

• The BEST management plan is:– A. ACE inhibitor as an outpatient– B. Beta blocker as an outpatient– C. Diuretic therapy as an inpatient– D. Repeat blood pressure in 1 to 2 weeks– E. Vasodilator therapy as an inpatient

Determine the Severity

• Severe HTN or hypertensive emergencies with significant symptoms of headache, epistaxis, diplopia, seizures, encephalopathy, hemiplegia, lethargy, or somnolence require hospitalization

Treatment

• Nonpharmacologic treatment– Lifestyle modifications or environmental changes

must be implemented or at least attempted!– Reducing sodium intake– Physical activity• If significant essential or severe HTN, avoid weight

lifting, body building, and strength training• Restriction based on the possibility of catastrophic

event

Question #5

• You have confirmed HTN in an 11-year-old girl. She has no complaints and feels fine. She is anxious to return to ballet class once a week. Her height and weight are at the 50%. Her BP is 125/83 mmHg (>95%), but otherwise her exam is normal. You have already performed BUN/Cr, CBC, UA and renal U/S, all of which were normal.

• Of the following, the next MOST appropriate step is:– A. Initiate captopril therapy and re-examine the girl in 1 week– B. Reassure the parents and re-examine the girl in 1 week– C. Hydralazine intravenous as an inpatient– D. Beta blocker as an outpatient– E. Restrict her from ballet class

Treatment• First-line– ACE inhibitors (ex: Captopril, Enalpril)

• Mechanism of action– Blocks the conversion of angiotensin I to angiotensin II and

inhibits kinase II

• SE = renal impairment, hyperkalemia, neutropenia, anemia, dry cough, angioedema, contraindicated in pregnancy

– Angiotensin receptor blockers• Mechanism of action

– Directly block the action of angiotensin II on their cell membrane receptors

• SE = renal impairment, hyperkalemia, neutropenia, anemia

Treatment (cont’d)

– Calcium channel blockers (ex: Nifedipine, Isradipine)• Mechanism of action

– Direct vasodilators by inhibiting calcium transport into vascular smooth muscle and other contractile cells

• SE = peripheral edema, dizziness, nausea, headache, flushing, weakness, postural hypotension

Treatment (cont’d)

• Second-line therapy– Beta-blockers (ex: atenolol, labetalol, metoprolol)• Mechanism of action

– Decreased cardiac output, decreased peripheral vascular resistance, inhibition of renin secretion, decreased circulating plasma volume, and inhibition of CNS sympathetic activity

• SE = CV changes, CNS effects, GI changes, hematologic effects, impotence• Contraindicated = asthma, Raynaud, CF, BPD,

uncompensated congestive heart failure, bradycardia, cardiogenic shock, athletes

Treatment (cont’d)

– Central alpha agonists (ex: Clonidine)• Mechanism of action

– Modulation of CNS centers for cardiovascular control and alpha-adrenoreceptor agonist

• SE = sedation, dry mouth, fatigue, hallucinations, rebound HTN

– Vasodilators (ex: Hydralazine, Minoxidil)• Mechanism of action

– Dilate the arteriolar resistance vessels, with a less pronounced effect on the venous capacitance vessels

• SE = headache, palpitations, tachycardia, flushing, fluid and sodium retention, lupus-like syndrome

Treatment (cont’d)

– Diuretics• Mechanism of action

– Inhibit the absorption of solute, resulting in decreased reabsorption of water and enhanced urine flow

• SE = fluid and electrolyte disturbance (hypokalemia, hypomagnesemia, hypercalcemia), metabolic disturbances, GI effects, ototoxicity• Potassium-sparing diuretics (spironolactone,

triamterene, amiloride)– Competative antagonist of aldosterone

RENAL STONE DISEASE

Definitions and Epidemiology

• Definitions– Urolithiasis= renal stones at any location– Nephrolithiasis= stones formed exclusively in the kidney– Nephrocalcinosis= calcium salts in the renal parenchyma

• Epidemiology– Uncommon disease in children, but increasing incidence– Males> females– Caucasians> African Americans

Some Basics to Start

• Crystalluria ≠ stone formation– Uric acid, calcium phosphate and calcium oxalate

crystals in the urine do not distinguish stone formers from non-stone formers

– Cystine and triple phosphate crystals indicative if underlying disease• Cystinuria, struvite stones

Some Basics to Start

• Formation of stones influenced by – Urine concentrations of stone forming substances• Calcium• Oxylate• Uric acid

– Urine concentrations of inhibitors• Citrate• Magnesium

– *Urine volume– Urine pH

Calcium Oxylate

Crystals Stones

Calcium Phosphate

Crystals Stones

Struvite

Crystals Stones

Cystine

Crystals Stones

Uric Acid

Crystals Stones

Causes of Renal Stone Disease

• Hypercalciuria• Hyperoxaluria• Hypocitraturia• Hyperuricosuira• Low urine volume

Question #6• A 2-year-old boy who has a history of poorly controlled seizures that are

managed with a ketogenic diet presents with increased fussiness and side pain. A urinalysis reveals:

– Specific gravity, 1.020– pH, 6– 3+ ketones– 2+ blood– Negative for protein, glucose, nitrite, and leukocyte esterase– 5 to 10 red blood cells/high-power field (hpf)– Fewer than 5 white blood cells/hpf

• Of the following, the MOST likely associated urinary finding in this patient is:– A. bacteruria – B. cystinuria – C. hemoglobinuria – D. hypercalciuria – E. hyperoxaluria

*Hypercalciuria

• Most common abnormality found in stoneformers (30-50%)– Idiopathic

• Encountered commonlyin a child with non-glomerular hematuria– Risk of stone formation 4-17% over the next 1-

11yrs

*Hypercalciuria

• Ca excretion> 4mg/kg/d or Ca/Cr> 0.2 – Child>2yo (younger children can have higher

values)• Sodium intake enhances calcium excretion• Calcium intake itself does not alter urinary

calcium concentration significantly– Low Ca diet not recommended

Hyperoxaluria

• Increased biosynthesis– Primary hyperoxaluria• Rare AR d/o; 2 types• Causes early and severe calcium oxalate stone

formation, nephrocalcinosis and ?renal failure

• Increased GI absorption– Associated with chronic diarrheal d/o• IBD, Celiac dz, CF

Hypocitrauria

• Citrate is a natural inhibitor of calcium phosphate and calcium phosphate crystal growth

Hyperuricosuria

• Uric acid stones are associated with – Excessive purine loads (high protein diet)– Low urinary pH

• Most important factor in determining the solubility of uric acid is pH

• Associated as much with calcium oxalate stone formation as uric acid stone formation

Cystinuria

• Rare AR defect– 2 different genetic defects types I-III

• Cystine stones characterized by their ability to form very large calculi that fill the collecting system (staghorn calculi)

• Screening test: cyanide-nitroprusside test

Question #7

• A 9 yo F with h/o spina bifida and frequent UTIs presents to the ED with worsening right-sided flank pain for the past week. Mom has also noticed some blood in her urine. On CT scan, she is found to have a large staghorn calculus in her right renal collecting system. Of the following, infection with which of the following bacteria most likely lead to stone formation?– A. E. coli– B. S. aureus– C. Proteus– D. Enterococcus– E. S. saprophyticus

*Struvite Stones

• Develop following change in urinary composition caused by urease-producing bacteria (alkaline urine with a high ammonium concentration)– Proteus– Pseudomonas– Klebsiella

• Can grow quickly and form staghorn calculi with bacteria being trapped in the stone– Associated with significant morbidity and mortality

• Children with neurogenic bladders, urinary diversions, and recurrent UTIs are at greatest risk

Question #8

• A 2 yo M presents to ED with a two week h/o of LLQ abdominal pain. CT of the abdomen shows a small stone in the left renal collecting duct and one in the ureter. Are you:– A. Surprised at the diagnosis; younger children with

renal stones usually present with flank pain that radiates to the groin.

– B. Not surprised at the diagnosis; younger children with renal stones typically present with non-specific pain localized to the abdomen, flank or pelvis.

*Clinical Presentation

• Adolescents present similarly to adults– Severe flank pain that radiates to the groin– Dysuria or frequency– Passage of blood or stones

• Younger children– Non-specific pain localized to the abdomen, flank, or

pelvis• Infants– Pain that mimics colic– UTI

*Evaluation

Lab Findings

• UA– Sterile pyuria– Gross or microscopic hematuria

• 30-90% of children with stones

– Crystalluria– High specific gravity

• Low urine output

– Abnormal urine pH• <6: uric acids stones• >7: calcium phosphate stones• >8: struvite stones

Lab Findings

• Electrolytes– RTA– Overall renal fxn– Ca and Phos abnormalities

Question #9

• A 10 yo M with h/o renal stones was found to have idiopathic hypercalciuria 6 months ago. Upon diagnosis, he was told to increase his fluid intake and eat a “no added salt” diet. Despite these changes, he was admitted to the hospital 1 mo ago due to another renal stone. Of the following, the most likely next step in this patient’s management would be the addition of:– A. HCTZ– B. Furosemide– C. Mannitol– D. Morphine– E. Potassium citrate

*Medical Management

Medical Management

• Struvite stones– Pose a serious therapeutic challenge due to their

large size and propensity to recur with incomplete removal

– Combination of medical and surgical management• Appropriate antibiotic therapy

Surgery

• Most stones <5mm pass spontaneously • Stones >5mm may require:– Percutaneous nephrolithotomy – Extracorporal shockwave lithotripsy– Retrograde endoscopic lithotripsy

HEMOLYTIC-UREMIC SYNDROME

Hemolytic-Uremic Syndrome (HUS)

• Triad– 1) Microangiopathic hemolytic anemia– 2) Thrombocytopenia– 3) Renal insufficiency

• 2 categories:– 1) typical HUS with diarrhea (D+)

• 90% of cases in US• Caused by shiga-toxin-producing strain of E. coli (STEC)

– O157:H7

– 2) atypical HUS without diarrhea (D-)

Shiga-toxin-producing E. Coli

• Also called enterohemorrhagic E. coli (EHEC)

• Infects children age 9 months to 4 years

• Summer and Fall• Primary reservoir is

cattle

Pathogenesis

• Thrombotic microangiopathy

• Enterocyte death and disruption of microvasculature hemorrhagic colitis

• Cell injury leads to intravascular creation of fibrin meshwork damages platelets and RBCs

Clinical Diagnosis

• Diarrheal prodrome– Abdominal pain– 35 to 90% with bloody diarrhea (self-limited)– Low grade fever

• Pale and icterus (from hemolysis)• HTN (volume overload and RAAS)• Petechiae (thrombocytopenia)• CNS involvement (15 to 20%; mostly seizure or

coma)

Question #10

• A mother brings in her 4-year-old daughter because of decreased energy following a 3-day history of diarrhea without vomiting. On PE, the girl's temp is 100.2°F, heart rate is 130 beats/min, RR is 18 breaths/min, and BP is 122/84 mm Hg. She has pale conjunctivae, a hyperdynamic precordium, and mild pretibial edema. Laboratory evaluation reveals BUN 40, Cr 1.4, Hgb 6, and Plts 90.

• The most likely additional lab abnormality is:– A. Low reticulocyte count– B. High LDH– C. Elevated PTH– D. Postitive Coombs– E. Prolonged PTT

Laboratory Findings• Microangiopathic hemolytic anemia– Hgb < 10– Negative Coombs– Schistocytes and helmet cells– Increased indirect bilirubin– Decreased haptoglobin– Increased LDH

• Thrombocytopenia• PT and PTT are normal• Hematuria and proteinuria• Elevated BUN/Cr• Low albumin

Question #11

• You are seeing a 4-year-old male in the ER with 3 days of diarrhea, fatigue, low grade fever, pallor, and petichiae. Mom is worried because she noticed blood in his stool this morning and now his urine output has decreased.

• Of the following, the BEST way to manage this patient is:– A. Start Loperamide po– B. Order platelet transfusion– C. Start Bactrim po– D. Volume expansion with isotonic fluids– E. Await results of stool culture before proceeding

Treatment

• Supportive– Volume expansion and maintenance fluids

(isotonic fluids)– Dialysis for BUN >80 to 100, fluid overload not

responsive to diuretics, electrolyte abnormalities– PRBCs for hematocrit below 15 to 18%– Avoid platelet transfusion unless active bleeding– Avoid antibiotics and antimotility agents during

diarrheal prodrome may worsen disease

ACUTE RENAL FAILURE

An Introduction…

• Definition:– Acute decline in renal function characterized by

increase in BUN and creatinine values, often accompanied by hyperkalemia, metabolic acidosis, and hypertension

• Three general forms:– Prerenal failure– Intrinsic renal failure– Postrenal failure

Question #12

• A 4 yo F presents to the ED with a one week h/o vomiting and diarrhea. For the past 1-2 days, Mom has noticed that her urine output has been decreasing. A BMP shows a creatinine of 1.3. Urine specific gravity is 1.030 with urine osmolarity of 600 mOsm. The FENa in this patient would likely be:– A. 6%– B. 4%– C. 3%– D. 2%– E. 0.5%

*Causes ofPrerenal Failure

**Think kidney hypoperfusion!!**

Pathophysiology- Prerenal

• Decreased intravascular volume decreased renal perfusion ischemic/ toxic injury to the renal cells decreased GFR relaxation of afferent arterioles, catecholamine/ vasopressin release, +RAA system, and prostacyclin release

Clinical Symptoms and Lab Findings

• Clinical Symptoms– Clinical Hx should reveal a cause of volume

depletion – Decreased urine output

• *Lab Findings

~Renal US and renal scan should be nml

UOP Sediments UNa FENa BUN/Cr

Prerenal ↓ Normal >400mOsm <10mEq/L <1% ↑

Question #13• A 3 yo F presents with a 4- to 5-day history of diarrhea, increased fussiness, and

decreased urine output over the previous day. On physical examination, her temperature is 37.5°C, heart rate is 120 beats/min, respiratory rate is 24 breaths/min, and blood pressure is 126/84 mm Hg. In addition, she has slightly pale, moist mucous membranes and a II/VI flow murmur, but no gallop or edema. Laboratory evaluation shows:

• Hemoglobin, 6.1 g/dL (61 g/L)• Hematocrit, 18.5% (0.185)• Platelet count, 68x103/mcL (68x109/L)• Blood urea nitrogen, 60 mg/dL (21.4 mmol/L)• Creatinine, 2.9 mg/dL (256.4 mcmol/L)

• Of the following, her FENa is most likely:– A. 0.5%– B. 4%– C. 1.5%– D. 1%– E. 0%

Intrinsic Renal Failure

• Pathophysiology– Ischemic/toxic insultcellular dysfunction with breakdown and necrosis decreased GFR

Clinical Symptoms and Lab Findings

• Clinical Symptoms– Clinical Hx should reveal a cause of injury– Decreased urine output• Oliguria (<0.5-1 mL/kg/h)• Anuria (no urine)

• *Lab FindingsUOP Sediments Uosm UNa FENa BUN/Cr

Prerenal ↓ Normal <10mEq/L <1% ↑

Renal ↓ RBC casts, granular

casts, RBC

<350mOsm >40mEq/L >2-3% ↔

Other Diagnostic Studies

• Renal scans– Ex: MAG3– Demonstrate extent of kidney function

• Renal biopsy– Rapidly increasing SCr– Establishing acute vs. chronic GN– Positive serology for systemic diseases

Question #14

• All of the following are possible causes of postrenal failure except:– A. Posterior urethral valves– B. UPJ obstruction– C. Urolithiasis– D. Nephrotic syndrome– E. Tumor

Postrenal Failure

• *Causes

• Pathophysiology– Obstruction of the ureter, bladder or urethra

increase in pressure proximal to the obstruction renal damage decreased GFR

Clinical Symptoms and Lab Findings

• History– Colicky abdominal pain– Gross hematuria– UOP variable

• PE– Palpable flank mass

• Labs– Urine sediment variable– Other parameters usually normal

Imaging

• Renal US– Dilated renal pelvis

• Radioisotope scan– Collection within the kidney (ureter, bladder) with

delayed or absent excretion of the isotope

Principles of Management

• Maintaining renal perfusion • Fluid/ electrolyte balance• Controlling BP• Treating anemia• Adequate nutrition• Adjusting meds for degree of renal impairment• Initiating renal replacement therapy when

indicated

Management

• Vasoactive agents– Given to improve BP and ensure adequate renal

perfusion– ?Efficacy of “renal dosing” of dopamine (0.5-3

mcg/kg/min)– ANP• Dilates afferent and constricts efferent arterioles

increase in GFR• More studies needed in children

Management

• *Fluids– Depend on patient’s hemodynamic status and

UOP• Oliguria + HD instability20mg/kg bolus isotonic fluids;repeat PRN

– Once IV volume replaced:• Fluid restrict to 400mL/m2/d+ UOP+ extrarenal losses

– Furosemide or mannitol to promote urination• Use of these alone does not change the need for renal

replacement therapies

Question #15

• A 5 yo M presents to the ED with a 2 week h/o increasing lethargy, weakness and pallor. A BMP shows a BUN of 65, creatinine of 3.2, and a K of 6.5. EKG shows peaked T waves. Of the following, which is part of the treatment regimen of hyperkalemia?– A. Calcium gluconate– B. Insulin and glucose– C. Sodium bicarbonate– D. Beta agonists– E. All of the above

Management

• *Electrolytes

Management

• Anemia– Transfusion indicated

• Active bleeding• HD instability• Hct<25%

• HTN– Usually secondary to volume overload or changes in

vascular tone• HTN crisis: IV labetolol, nicardipine, enalaprilat, diazoxide• Less severe HTN: short-acting nifedipine

Management

• *Nutrition– Patients in a catabolic state– Diet with following own• 70% calories from carbs• <20% lipids• Biologic value proteins 0.5-2g/kg/d

• *Medications– Dosage or interval should be adjusted for degree

of renal impairment

Management

• Renal replacement therapy– Indications• CHF• Anemia• Hyperkalemia• Severe acidosis• Pericarditis• Inadequate nutrition

– CVVH, CAVH, hemodialysis, peritoneal dialysis

Prognosis

• Recovery: days weeks• Prognosis depends on:– Need for dialysis– Time between onset and presentation to medical

care– Underlying disease

• Multisystem organ failure and young age at presentation= poor prognostic factors

HAPPY HOLIDAYS!!!