Topics that our residents did not perform well on during the In-Training exam

• Diagnosis of primary hyperaldosteronism in metabolic alkalosis• Predict the composition of renal calculi in the setting of chronic UTI• Recognize the limitations of the MDRD equation in estimating GFR• Distinguish between office and home hypertension• Management of hyperphosphatemia in a patient with CKD• diagnose psychogenic polydipsia• Treat hyponatremia• Diagnose mixed acid/base disturbances• Diagnose membranous GN• Evaluate PCKD• Diagnose IgA nephropathy• Manage proteinuria in CKD

Question 1

A 45 y.o. woman is found to have a blood pressure of 150/95 mmHg during office visits on an intermittent basis over 3 months. Her blood pressure on two other office visits has been found to be within normal limits. She is in excellent health and on no medications. Her father has a history of hypertension.

Question 1

The physical exam is remarkable only for a blood pressure of 150/90 mmHg. Labs including electrolytes, BUN, creatinine and urinalysis are normal. An ECG is normal.

Which of the following is the most appropriate next step in the management of this patient?

a. Ambulatory BP monitoringb. Echocardiographyc. Ongoing office follow up.d. Start hydrochlorothiazide

Question 2A 65 y.o. male is referred for evaluation of edema and proteinuria. He

complains of fatigue, but otherwise is asymptomatic. On exam the BP is 150/80. There is 1+ ankle edema. Labs show hemoglobin 10 (MCV 74, RDW 20); urine protein:creatinine ratio is 4.4 mg/gm, serum creatinine is 1 mg/dL, and cholesterol is 320 mg/dL. Serum complement levels are normal. Urinalysis shows 3+ protein, hyalofatty casts and oval fat bodies.

Which of the following is the most likely cause of this patient’s renal symptoms?

A. Minimal change glomerulopathyB. FSGSC. Membranous glomerulopathyD. IgA nephropathyE. ANCA-associated GN

Question 3A 19 y.o. female is evaluated for sudden onset periorbital and pretibial

edema. 3 weeks ago she was diagnosed with an URI that has since resolved. On PE the BP is 150/100. A soft S3 gallop is present. There are crackles at both lung bases. The liver is enlarged and tender. There is bilateral pitting pretibial edema. There is no rash. Labs show creatinine 1.5, albumin 3.8. C3 and C4 are low. Urinalysis shows rare dysmorphic red cells and trace protein.

Which of the following is the most likely diagnosis?A. IgA nephropathyB. Goodpasture's syndromeC. ANCA vasculitisD. Postinfectious GNE. SLE nephritis

Question 4 A 19 y.o. female presents with a several month history of symmetric

arthralgias, Raynaud’s phenomenon, and a Coomb’s positive hemolytic anemia. On physical exam she has a malar rash that crosses the nasal labial folds. The heart and pulmonary exams are unremarkable. Her abdomen is benign. There is 1 + leg edema. Urinalysis shows red cell casts and 2+ protein. A kidney biopsy shows immune complex focal proliferative glomerulonephritis.

Which if the following tests provides the most additional diagnostic information?

A. Low C 3 and C4B. Positive ANAC. Positive ss-DNAD. Positive anti-Smith antibodyE. Positive ds-DNA

Question 5

A 58 year old male with stage IV CKD secondary to diabetic nephropathy presents for routine follow up. Laboratory studies show calcium 8.2 mg/dL, phosphorus 5.8 mg/dL, PTH 456 pg/mL, 25-OH vitamin D 42 ng/mL, 1,25-(OH)2-vitamin D 58.

Which of the following is the most appropriate next step in the management of this patient?

A. Start a 1,25-dihydroxy-vitamin D analogueB. Start cinacalcetC. Dietary phosphate restrictionD. Phosphate binder therapyE. Parathyroidectomy

Question 6A 38 y.o. man with a history of chronic liver disease secondary to hepatitis C is

treated with a 24-wk course of pegalated IFN combined with ribavarin. Four weeks after completing treatment he complains of proximal muscle weakness. On PE the BP is 120/80, pulse 110, RR 18. His general exam is unremarkable. On neurologic exam he has symmetric proximal weakness 3/5. Labs show Na 142, K 2.1, Cl 104, HCO3 20, creat 1. Urine Na 96, urine K 10, urine Cl 110, urine osm 585.

Which of the following is the most likely diagnosis?

A. Distal renal tubular acidosis (type I)B. VomitingC. Diuretic abuseD. IFN complicationE. Hypomagnesemnia

Question 7A 45-yr-old previously healthy woman who weighs 50 kg undergoes surgery for a

ruptured ovarian cyst. During surgery, she is given 2 L of lactated Ringer solution, and she is given 5% dextrose in 0.45% NaCl with 20 mEq/L KCl at 250 ml/h postoperatively. Forty-eight hours after surgery, she complains of headache and vomiting. BP is 140/80 mmHg. She is alert and oriented, and the general physical and neurologic examinations are unremarkable. Laboratory data reveal the following: Serum Na 115 mEq/L, plasma osmolality 241 mOsm/kg H2O, and urine osmolality 850 mOsm/kg H2O. The patient is not taking anything by mouth.

In addition to stopping the 5% dextrose in 0.45% NaCl infusion, which ONE of the following would be the MOST appropriate treatment?

A. 5% dextrose in 0.9% saline with 20 mEq KCl at 250 ml/hB. 5% dextrose in 0.9% saline with 20 mEq KCl at 50 ml/hC. 3% saline at 100 ml/h plus intravenous furosemide until serum sodium

concentration is 132 mEq/LD. 3% saline at 50 ml/h plus intravenous furosemide until the serum sodium is 120

mEq/L

Treatment of Severe and Moderate Symptoms in SIADH

TreatmentGoals of Therapy

General Specific

• Discontinue

contributing

medications

• Fluid

restriction

Severe•3% saline

•Furosemide

• Until symptoms

resolve• ~10 mEq/L in 24• ~18 mEq/L in 48

Moderate

•3% saline

•Furosemide

•?Vaptans

• Until symptoms

resolve• <10 mEq/L in 24• <18 mEq/L in 48

Treatment of Symptomatic Hyponatremia

• Do not use equations• Start 3% saline at 1 ml/kg/hr-this will increase

the plasma sodium on average by 1 mEq/L/hr• Monitor the patient

– Measure the plasma sodium every hour initially– Stop therapy when symptoms resolve– Rise in plasma Na of about 5 mEq/L usually sufficient

• Treat in ICU or step-down setting

Question 8

A 45 year old Caucasian male is referred for further evaluation of a persistent elevation in the serum creatinine of 1.4 mg/dL. The physical exam show a blood pressure of 130/80 mmHg and is otherwise unremarkable. The urinalysis is normal. The estimated GFR is 56 ml/min per the MDRD equation. Renal ultrasound shows the right kidney 11.2 cm in size and the left kidney 10.9 cm in size. The urine protein:creatinine ratio returns at 0.056.

Which of the following is the most appropriate step in this patient’s management?

A. Start enalapril B. 24 hour urine for creatinine clearanceC. Start a thiazide diureticD. No further evaluation

Key Points

• The estimated GFR should be calculated using the MDRD equation whenever a serum creatinine is measured in steady state conditions for patients with an eGFR < 60 ml/min.

• The MDRD eGFR can be falsely low in individuals with large muscle mass and near normal GFRs.

• Consider 24 hour urine collections for creatinine clearance in the following populations:– Near normal GFR– Extremes of age and weight– Amputees– Pregnant women – Cirrhotics

Question 9A 46 y.o. male is hospitalized for severe necrotizing pancreatitis. He is placed on NG

suction and over the first 24 hours of hospitalization he receives 6 liters of NS and then NS at 100 mL/hour. Over the next 24 hours his urine output increases to > 3 liters per day and his plasma sodium concentration rises from 145 meq/L on admission to 153 meq/L.

On exam the blood pressure is 140/90. Chest is clear . There is no edema.

Labs show sodium 153, potassium 3, chloride 112, bicarbonate 24, BUN 49, creatinine 1.1, urine sodium 50, urine potassium 20, urine osmolality 500 mosm/kg.

Which of the following is the most likely cause of this patient’s polyuria?

A. Central diabetes insipidusB. Nephrogenic diabetes insipidusC. Post obstructive diuresisD. Solute diuresis

Polyuria

• Urine output exceeding 3 L per day

• Etiology– Water diuresis

• diabetes insipidus– central– nephrogenic

• primary polydipsia

– Solute diuresis

Evaluation of Polyuria

Urine Osmolality

< 250 mosm/kg > 300 mosm/kg

Water Diuresis Solute Diuresis

Urine and Plasma Osmolality in Disorders of Water Balance

1000

800

600

400

200

280 285 290 295 300Posm(mosm/kg)

Uo

sm(m

osm

/kg)

Normal

Primary polydipsia

Central DI

Nephrogenic DI

WaterDeprivation dDAVP

Question 10A 56 year old female presents with a 2 day history of

weakness. On physical exam she is diffusely weak and is unable to sit up. The blood pressure is 160/95 mmHg. There is no edema.

140 96 20 1.9 32 1.4

Urine [Na+] = 75 mEq/LUrine [Cl-] = 100 mEq/LFeK = 20%

Which of the following is the most likely diagnosis?

A. VomitingB. Gordon syndromeC. HyperaldosteronismD. Gitelman syndrome

Metabolic Alkalosis

BPVolume status

BP Normal or Low Effective circulating volume

BP High ECF

Loss of HClLoss of Volume (Na+/H20)

Loss of Gastric secretions(vomiting, NG suction)DiureticsBartter syndromeGitelman syndrome

Primary Hyperaldosteronism

Metabolic Alkalosis: Loss of Gastric Secretions-Maintenance Phase

Volume Contraction

Reabsorption of sodium,chloride, and bicarbonate

along the nephron

Elimination of sodium, chloride, and bicarbonate

from the urine

Secondary increasein aldosterone

Increased H+

Excretion

Metabolic alkalosis

Paradoxicalaciduria

Variation in Urine Electrolytes in Vomiting

Phase [Na+]

mEq/L

[K+]

mEq/L

[Cl-]

mEq/L

[HCO3-]

mEq/L

pH

Units

Generation >15 >15 <15 >15 >6.5

Maintenance <15 Variable <15 <15 <5.5

Metabolic Alkalosis: Primary Hyperaldosteronism

IncreasedAldosterone

SodiumRetention

Volume Expansion

•Starling Forces in Proximal tubule•Atrial Natriuretic Peptide•Down regulation of NaCl CT in DCT

Hypertension

Natriuresis

Na+

bala

nce

-200

200

Days2 4 6 8 10 12 14 16 18

Uri

ne [

Na

+]

mEq/L

10

15

20

EC

F V

ol

(L)

18

21

Mean a

rteri

al

Pre

ssure

100

110

90

15

0

Aldosterone

Aldosterone Escape

Urine Na+ and Cl- in the Differential Diagnosis of Metabolic Alkalosis and Hypokalemia

Urine ElectrolytesNa+ Cl-

Condition (meq/L)

VomitingAlkaline urine >15 <15Acidic urine <15 <15

DiureticDrug active >15 >15Remote use <15 <15

Hyperaldosteronism >15 >15

Question 11A 42 y.o. female is evaluated for minimal edema and a urinary protein excretion

of 5 gm/24 hours. As a child she had frequent urinary tract infections and underwent a surgical procedure to reimplant the ureters to prevent reflux. On PE the BP is 140/95. There is trace peripheral edema. Labs show creatinine 1.5, albumin 3.4, Urinalysis shows 3 + protein and oval fat bodies.

Chest x-ray is normal. Renal US shows a normal left kidney and the right kidney small and difficult to visualize.

Which of the following is the most likely cause of the proteinuria?

A. Minimal change diseaseB. Membranous nephropathyC. FSGSD. Membranoproliferative GN

Question 12A homeless man is discovered unconscious in the park and is brought to the emergency

department. He wreaks of alcohol, is unkempt, and is incoherent. Physical examination shows a BP of 90/50 mmHg, heart rate of 120 bpm, temperature of 39°C, slight scleral icterus and dullness, and bronchial breath sounds over the right lower lung fields. Laboratory data reveal the following: Serum Na 131 mEq/L, K 2.9 mEq/L, Cl 70 mEq/L, CO2 21 mEq/L, blood urea nitrogen 34, creatinine 1.4 mg/dl, glucose 240 mg/dl, serum osmolality 320 mOsm/kg H2O, serum ketones weakly positive, pH 7.53, PaCO2 25 mmHg, PaO2 60 mmHg, and serum albumin 3.8 g/dl.

Which ONE of the following choices BEST describes his acid-base disturbance?

A. Metabolic acidosisB. Respiratory alkalosisC. Metabolic acidosis and respiratory alkalosisD. Metabolic acidosis and metabolic alkalosisE. Metabolic acidosis, metabolic alkalosis, and respiratory alkalosis

Question 1323-year-old Caucasian female referred for further evaluation of hypokalemic acidosis. She

was in her usual state of excellent health with normal growth and development until her second month of pregnancy. She had a spontaneous miscarriage, and was found to have a serum potassium of 3.2 mEq/L and a bicarbonate level of 19 mEq/L during a hospitalization for a D and C. She was treated with oral potassium and bicarbonate supplements and then weaned these off after 4 months of therapy. Six weeks later, she developed myalgias and collapsed due to profound weakness. She was found to have a serum bicarbonate level of 14 mEq/L with a serum potassium of 1.9 mEq/L.

140 114 13 Calcium 9.11.9 14 1 Phosphorus 3.5ABG-pH 7.29, PCO2 30, pO2 100Urine K 46 Urine Na 36 Urine Cl 42 Urine Osm 580 UA ph 6.8 trace protein No casts 10-15 white cells per high power field

Which of the following is the correct diagnosis?A. Type IV RTAB. DiarrheaC. Type I RTAD. Renal tubular alkalosisE. Proximal RTA

Practical Approach (Hyperchloremic metabolic acidosis)

Urinary Anion Gap

Negative PositiveType 2 RTA

Diarrhea

DKA/Toluene

HCl (Hyperalimentation)

Urine pH and Plasma K

Urine pH < 5.5, K Urine pH > 5.5, K nl/low Urine pH > 5.5, K

Type 4 Type 1 (secretory defect Type 1 (voltage)

or back-leak)

Type I Classic Distal RTA-Mechanism 1

ATPase

ATPase

ATPase

Tubular lumenPeritubularCapillary

K+

H+

OH- + CO2 HCO3-

T

Cl-

H2O

H+ 3Na+

2K+

Cl-

K+

Na+

ATPase

3Na+

2K+

R-Aldo

(-)

(-)

(-)

(-)H+

RetentionK+ WastingUrine pH > 5.5Ca-P stones

Na+

Type I Classic Distal RTA-Mechanism 2

ATPase

ATPase

ATPase

Tubular lumenPeritubularCapillary

K+

H+

OH- + CO2HCO3-

T

Cl-

H2O

H+ 3Na+

2K+

Cl-

K+

Na+

ATPase

3Na+

2K+

R-Aldo

(-)

(-)

(-)

(-)H+

RetentionK+ WastingUrine pH > 5.5Ca-P stones

Na+

Type I Distal RTA-Mechanism 3

ATPase

ATPase

ATPase

Tubular lumenPeritubularCapillary

K+

H+

OH- + CO2HCO3

-

T

Cl-

H2O

H+ 3Na+

2K+

Cl-

K+

Na+

ATPase

3Na+

2K+

R-Aldo

(-)

(-)

(-)

(-)

H+Retention

K+ WastingUrine pH > 5.5Ca-P stones

Na+

H+

Backleak of H+

Question 14A 17-yr-old girl complains of profound weakness, dizziness, and polyuria. She

is taking no medications and has no gastrointestinal complaints. Pertinent clinical finding is BP of 90/50 mmHg with orthostatic dizziness. Laboratory data reveal the following: Na 140 mEq/L, K 2.5 mEq/L, Cl 100 mEq/L, CO2 33 mEq/L, blood urea nitrogen 25 mg/dl, and creatinine 0.7 mg/dl. A 24-h urine collection reveals the following: Sodium 90 mEq, potassium 60 mEq, Cl 110 mEq, and calcium 280 mg. Plasma renin and aldosterone are elevated.

These findings are MOST suggestive of which ONE of the following?

A. Adrenal adenomaB. Gitelman syndromeC. Bartter syndromeD. Licorice ingestionE. Surreptitious vomiting

Urine Na+ and Cl- in the Differential Diagnosis of Metabolic

Alkalosis and Hypokalemia

Urine ElectrolytesNa+ Cl-

Condition (meq/L)

VomitingAlkaline urine>15 <15Acidic urine <15 <15

DiureticDrug active >15 >15Remote use <15 <15

Hyperaldosteronism >15 >15

Question 15A 72-yr-old woman who has multiple sclerosis and weighs 50 kg

receives 400 mg/kg intravenous immunoglobulin infused for 3 h. At the end of the infusion, she has an acute and dramatic worsening of neurologic symptoms. She is suddenly unable to bear weight or coordinate arm and leg movements and describes paresthesias and hyposthesias of all extremities. Blood chemistries are normal except for a serum sodium of 130 mEq/L and a plasma osmolality of 300 mOsm/kg.

Which ONE of the following is the BEST treatment for this patient?

A. 3% saline in 50-ml bolusB. 3% saline in 150-ml bolusC. 3% saline at 50 ml/h for 4 hD. 0.9% saline, 1000 ml, infused as rapidly as possible with furosemide

80 mg intravenouslyE. Make patient n.p.o. and observe

Question 16A 49 y.o. female is admitted to the hospital because of severe right sided abdominal pain

requiring administration of narcotic analgesics. The patient is unable to provide a complete medical history, but reports that she has had seizures for as long as she can remember.

Physical exam reveals papular skin lesions in the malar area. Bilateral flank masses are noted. There is a 2-cm periungual nodular lesion on the right great toe.

Hematocrit is 25%. Serum creatinine is 5.5 mg/dL. CT of the abdomen without contrast reveals enlarged kidneys with bilateral renal cysts of varying size in the cortex and the medulla; several variably sized masses with densities identical to perinephric fat are also detected in areas not involved with cysts.

Which if the following is the most likely diagnosis?A. ADPCKDB. Von Hippel-Lindau diseaseC. Medullary cystic kidney diseaseD. Tuberous sclerosisE. Bilateral renal dysplasia

Question 17A 66-year-old man comes for a follow-up

examination for elevated blood pressure. He has a history of chronic kidney disease and hypertension well controlled with hydrochlorothiazide. One week ago, he was evaluated in the office after obtaining several home blood pressure measurements averaging 145/90 mm Hg. Enalapril was added at that time. He has felt well and has no history of cough, lower-extremity edema, or dyspnea. He also takes low-dose aspirin.

On physical examination today, temperature is normal, blood pressure is 126/70 mm Hg, respiration rate is 18/min, and pulse rate is 78/min and regular. On cardiac examination, the point of maximal impulse is laterally displaced and an S4 gallop is heard. There is no edema.

1 week ago Today

Potassium 4.5 meq/L 5.2 meq/L

Creatinine 1.2 mg/dL 1.5 mg/dL

Urine albumin:creatinine ratio 200 mg/g

In addition to dietary potassium restriction, which of the following is the most appropriate next step in this patient’s management?

A. Add diltiazemB. Discontinue enalapril; switch to metoprololC. Repeat creatinine and potassium measurement in 1 weekD. Kidney arteriography

Question 18

78-year-old female with a history of longstanding type II diabetes mellitus, hypertension, Takotsubo cardiomyopathy with an EF of 38%, and stage III CKD is seen for routine follow up. From a symptomatic standpoint she was doing well without complaints of chest pain, PND or orthopnea. She has a history of hyperkalemia while on ACE inhibitors, and her heart failure has been managed with hydralazine, furosemide, isosorbide dinitrate, and metoprolol.

BP 128/72, pulse 53/min. No JVD. Chest is clear. Cardiac exam shows bradycardia and a I/VI systolic murmur heard along the left sternal border. No edema.

Lab Result

Sodium 141

Potassium 6.6

Chloride 104

Bicarbonate 26

BUN 66

Creatinine 1.55

eGFR 39

Lab Result

Calcium 9.8

Phosphorus 4.2

Glucose 131

Hemoglobin 9.6

Urine protein:creatinine ratio

0.486

Urinalysis Specific gravity 1.014, pH 5.5, 1+ protein. No cells. Few fine granular casts.

Question 18

Which of the following is the most important factor in the pathogenesis of the hyperkalemia?

A. Decreased GFR

B. Volume depletion

C. Hyporeninemic hypoaldosteronism

D. Redistribution of potassium from cells to the extracellular fluid space

Question 18

Which Patients are at Risk for Hyperkalemia?

• eGFR < 30 ml/min• Diabetes mellitus• Human immunodeficiency virus infection• Congestive heart failure• Older adults• Dietary indiscretion• Medications

Evaluation of Hyperkalemia

K> 5.5Exclude laboratory error• Hemolysis• Excessive tourniquet time• Severe leukocytosis or thrombocytosis

Redistribution• Tissue injury (rhabdomyolysis, tumor lysis, hemolysis, GI bleed)• Insulin deficiency• Metabolic acidosis• Hyperosmolarity• Drugs (digoxin toxicity)• Hyperkalemia periodic paralysis

Decreased renal excretion

Renal failureGFR < 20 ml/min

Decreased urine flowSevere hypovolemia Hyperkalemia distal RTA

Causes of Hyperkalemic Distal Renal Tubular Acidosis

Palmer B. N Engl J Med 2004;351:585-592

Causes of Hyperkalemic Distal Renal Tubular Acidosis

Hypoaldosteronism

Low renin• Medications NSAIDs Cox-2 inhibitors Calcineurin inhibitors Beta-blockers• Diabetes mellitus• HIV infection

High renin• Adrenal insufficiency• Congenital enzyme defects• Medications

• ACE inhibitors• ARBs• Heparin• Ketoconazole

Collecting Duct Defects• Medications

• Amiloride• Triamterene• Spironolactone• Eplerenone• Trimethoprim• Pentamidine

• Tubulointerstitial disease• Urinary tract obstruction• Defective MR receptor

Hyperkalemia: Key Points

• After excluding redistribution and laboratory error, decreased renal excretion of potassium is the most common cause of hyperkalemia– Drugs, collecting duct defects, and hyporeninemic

hypoaldosteronism are the most common causes

• Therapy of hyperkalemia associated with hyporeninemic hypoaldosteronism includes:– Modify contributing medications– Dietary potassium restriction (~3000 mg per day or 60 mEq)– Diuretics– Sodium polystyrene

Question 19A 26 year old female presents with a history of intermittent tea-colored

urine, often becoming apparent a day or two after onset on upper respiratory tract infections. On exam the blood pressure is 140/90 mmHg, heart and lungs normal, and there is no peripheral edema. There is no rash or synovitis.

Urinalysis reveals trace protein and 5-10 dysmorphic red cells per high power field. The serum creatinine concentration is 0.6 mg/dL. Anti-nuclear antibodies and anti-neutrophil antibodies return negative. Serum complement levels are normal.

Which one of the following represents the most likely diagnosis? A. membranoproliferative glomerulonephritisB. membranous nephropathy C. IgA nephropathy D. post-infectious glomerulonephritis

Question 20

A 49-year-old white female who has a history of T12 paraplegia secondary to spinal cord injury and neurogenic bladder presents with gross hematuria. On physical exam there is left flank pain. Urinalysis shows pH 7.4, 2+ leukocyte esterase, 1+ nitrite, 15-20 white cells per hpf, and 1 + bacturia.

Question 20-KUB

Question 20

Analysis of the fragments of the patient’s stones is likely to reveal which one of the following components?

A. Calcium oxalate

B. Calcium phosphate

C. Cystine

D. Magnesium ammonium phosphate

E. Uric acid

Question 21A 65 year old man presents for follow up after presenting with a left leg

deep venous thrombosis 3 weeks ago. He was treated with low molecular weight heparin followed by warfarin. He has been in good health, and has a remote 30 pack year history of smoking. His physical exam demonstrates increased non-pitting edema in the left lower leg.

Laboratory studies show a serum creatinine of 1.4 and normal complete blood count. INR is 2.2. Urinalysis shows trace protein and 1+ blood with 5 red cells per high power field. The urine protein:creatinine ratio is 0.349.

Further chart review show that a urine dipstick performed 6 months ago showed 1+ blood and trace protein.

Which of the following is the most appropriate next step in the patient’s management?

A. Discontinue warfarinB. Kidney biopsyC. CiprofloxacinD. Cystoscopy

Urinary Albumin-Total Protein Ratio in Distinguishing Between Glomerular and

Non-glomerular Hematuria

A value > 0.59 suggest glomerular hematuria

Am J Kidney Dis 2008; 52:235-241

Question 22A 50-yr-old man with hemophilia complicated by HIV/AIDS and cirrhosis caused by

hepatitis C is admitted for renal failure. He is treated with furosemide and spironolactone for management of ascites and sulfamethoxazole and trimethoprim for prophylaxis against Pneumocystis jiroveci pneumonia. There is no history of alcoholism. On admission, BP is 98/62 mmHg, and physical examination shows scleral icterus, stigmata of cirrhosis, an abdominal fluid wave, and pitting edema of his lower extremities. He is alert and oriented but has asterixis.

Laboratory data show serum Na 128 mEq/L, K 5.7 mEq/L, Cl 95 mEq/L, CO2 23 mEq/L, BUN 49 mg/dl, glucose 110 mg/dl, and creatinine 2.3 mg/dl, and plasma osmolality 290 mOsm/kg. Urine osmolality is 580 mOsm/kg. Other laboratory values included urine Na 53 mEq/L, random cortisol 25 g/dl, uric acid 14.2 mg/dl, serum triglycerides 50 mg/dl, total cholesterol 95 mg/dl, total protein11.7 gm/dl, and albumin 2.4 gm/dl.

Which ONE of the following is the MOST likely cause of the patient’s hyponatremia?

A. Addison diseaseB. Trimethroprim therapyC. Syndrome of inappropriate antidiuretic hormone secretion (SIADH)D. Pseudohyponatremia

Question 23 A 46-year-old woman comes to the emergency department because of new-onset seizures. During

physical examination, she is slightly confused. Blood pressure is 136/80 mm Hg. No neurologic abnormalities are noted, and other physical findings are normal.

Laboratory studies: Serum creatinine 1.6 mg/dL Serum electrolytes   Sodium 140mEq/L   Potassium 4.8 mEq/L   Bicarbonate 22 mEq/L Serum

albumin 4.6 g/dL Serum calcium 9.1 mg/dL Serum magnesium 1.8 mEq/ L Serum phosphorus 4.8 mg/dL

Gadolinium-enhanced magnetic resonance imaging (MRI) of the head is performed, and the patient is admitted to the hospital. Repeat laboratory studies obtained 90 minutes after the MRI are shown below.

Serum sodium 139 mEq/L Serum potassium 4.9 mEq/L Serum bicarbonate 21 mEq/L Serum calcium 6.2 mg/dL.

Which of the following is most appropriate at this time?

(A) No treatment is indicated(B) Administer 10% calcium gluconate, 10 mL intravenously over a five-minute period(C) Administer magnesium sulfate, 2 g intravenously over a 20-minute period(D) Initiate hemodialysis using a high calcium dialysate(E) Start calcium carbonate, 100 mg orally daily, and calcitriol, 0.25 μg orally daily

Question 24A previously healthy 27-year-old woman who is running a marathon

collapses as she approaches the 25-mile marker and is rushed to the medical tent. During physical examination, she is barely arousable. Pulse rate is 110 per minute, and blood pressure is 96/65 mm Hg. The skin is dry. Crackles are audible at the lung bases. Other physical findings are normal. There are no facilities for measuring the patient's serum sodium level.

An intravenous catheter is inserted.

Which of the following is the most appropriate initial intravenous fluid therapy for this patient?

(A) 0.45% sodium chloride, 500 mL(B) 0.9% sodium chloride, 500 mL(C) 3.0% sodium chloride, 100 mL

Question 25A 36-year-old man is found to have a serum creatinine level of 4.2 mg/dL during routine pre-

employment evaluation. He reports no symptoms except for frequent episodes of gout over the past 19 years and three-times-nightly nocturia. Two of his four younger siblings have had gout; he does not know the status of their kidney function. His mother is healthy; he has lost contact with his father.

Blood pressure is 110/70 mm Hg. Laboratory studies disclose hyperuricemia that is associated with no other abnormalities except for mild metabolic acidosis and elevated serum creatinine; other laboratory findings are shown below.

Hematocrit 34% Hemoglobin 10.2 g/dL Urinalysis Specific gravity, 1.006; protein trace; 0-2 RBCs,1-3 WBCs/hpf

Ultrasonography reveals 9-cm echogenic kidneys with several small peripelvic cysts bilaterally.

Which of the following is the most likely diagnosis?

(A) Autosomal dominant polycystic kidney disease(B) Autosomal recessive polycystic kidney disease(C) Medullary cystic kidney disease, type 2(D) Medullary sponge kidney(E) Tuberous sclerosis