ITE Nephrology and Hypertension Questions and Answers — Questions and Answers
Question 1: A 68-year-old male in the ICU for septic shock develops a rise in serum creatinine from a baseline of 1.0 mg/dL to 3.5 mg/dL over 48 hours. His blood pressure has required vasopressors. A urinalysis is performed. Which of the following findings would be most indicative of acute tubular necrosis (ATN) as the cause of his kidney injury?
- White blood cell casts and eosinophiluria
- Red blood cell casts and dysmorphic red cells
- Muddy brown granular casts (Correct answer)
- Hyaline casts and a fractional excretion of sodium (FENa) <1%
Correct answer: Muddy brown granular casts
Muddy brown granular casts are the pathognomonic finding for acute tubular necrosis (ATN). They are formed from sloughed, necrotic tubular epithelial cells. Sepsis and hypotension are classic causes of ischemic ATN. White blood cell casts and eosinophiluria suggest acute interstitial nephritis. Red blood cell casts indicate a glomerular process (glomerulonephritis). Hyaline casts are nonspecific, and a FENa <1% points towards a prerenal etiology, not intrinsic kidney injury like ATN.
Question 2: A 55-year-old man with stage 4 chronic kidney disease (eGFR 25 mL/min/1.73m²) presents for follow-up. His labs show a serum calcium of 8.2 mg/dL (low), serum phosphate of 5.8 mg/dL (high), and an intact PTH level of 450 pg/mL (high). According to the KDIGO guidelines for CKD-Mineral and Bone Disorder (CKD-MBD), what is the most appropriate initial intervention?
- Initiation of an oral phosphate binder (Correct answer)
- Initiation of cinacalcet
- Initiation of active vitamin D (calcitriol)
- Referral for parathyroidectomy
Correct answer: Initiation of an oral phosphate binder
According to the KDIGO guidelines, the initial management of secondary hyperparathyroidism with hyperphosphatemia in CKD is to lower the elevated phosphate levels. This is achieved through dietary phosphate restriction and the initiation of phosphate-binding agents. Using calcitriol or cinacalcet before controlling phosphate levels can be less effective and may worsen the calcium-phosphate product. Parathyroidectomy is reserved for severe, refractory hyperparathyroidism.
Question 3: A 25-year-old male presents with gross hematuria and mild bilateral flank pain that began 2 days after the onset of an upper respiratory infection. His blood pressure is 150/95 mmHg. Urinalysis reveals numerous red blood cells, red blood cell casts, and 2+ proteinuria. What is the most likely diagnosis?
- IgA nephropathy (Correct answer)
- Post-streptococcal glomerulonephritis
- Minimal change disease
- Membranous nephropathy
Correct answer: IgA nephropathy
The presentation of gross hematuria occurring concurrently with or just a few days after an upper respiratory tract infection (synpharyngitic hematuria) is the classic presentation for IgA nephropathy. Post-streptococcal glomerulonephritis typically has a longer latent period of 1-3 weeks after the infection. Minimal change disease and membranous nephropathy are causes of nephrotic syndrome and typically present with heavy proteinuria and edema, not a nephritic picture with prominent hematuria and RBC casts.
Question 4: A 60-year-old man with a history of alcohol use disorder is found to have a serum sodium of 112 mEq/L. He is lethargic but arousable. To minimize the risk of osmotic demyelination syndrome, which of the following represents the safest therapeutic goal for correction?
- Increase serum sodium to 130 mEq/L within the first 24 hours.
- Limit the increase in serum sodium to no more than 6-8 mEq/L in the first 24 hours. (Correct answer)
- Administer a 500 mL bolus of 3% hypertonic saline over one hour.
- Increase serum sodium by 12-14 mEq/L in the first 24 hours.
Correct answer: Limit the increase in serum sodium to no more than 6-8 mEq/L in the first 24 hours.
Rapid correction of chronic hyponatremia (duration > 48 hours) can lead to osmotic demyelination syndrome (ODS). Current guidelines recommend a slow correction rate to allow the brain to adapt. The goal is to limit the increase in serum sodium to no more than 6-8 mEq/L in any 24-hour period, especially in high-risk patients (e.g., alcoholism, malnutrition). Rates exceeding 10-12 mEq/L/day significantly increase the risk of this severe neurologic complication.
Question 5: A 34-year-old female is diagnosed with hypertension, with blood pressures consistently around 160/105 mmHg despite therapy with two antihypertensive agents. She has no family history of hypertension. On physical examination, a faint bruit is audible in the right upper abdominal quadrant. Which of the following is the most appropriate next step to investigate the likely cause of her secondary hypertension?
- 24-hour urine collection for metanephrines
- Overnight dexamethasone suppression test
- Plasma aldosterone-to-renin ratio
- Renal artery duplex ultrasound (Correct answer)
Correct answer: Renal artery duplex ultrasound
The patient's demographic (young female), resistant hypertension, and the presence of an abdominal bruit are highly suggestive of renal artery stenosis due to fibromuscular dysplasia (FMD). A renal artery duplex ultrasound is an excellent non-invasive initial test to screen for this condition. The other options are used to investigate other causes of secondary hypertension: pheochromocytoma (metanephrines), Cushing's syndrome (dexamethasone suppression), and primary aldosteronism (aldosterone-renin ratio), which are less likely given the specific clinical clue of an abdominal bruit.
Question 6: A patient with stage 5 CKD presents to the emergency department with altered mental status. Which of the following findings represents the most urgent indication to initiate hemodialysis?
- Blood urea nitrogen (BUN) of 120 mg/dL
- Serum creatinine of 9.0 mg/dL
- Uremic pericarditis with a friction rub (Correct answer)
- Refractory peripheral edema
Correct answer: Uremic pericarditis with a friction rub
While elevated BUN and creatinine, and fluid overload are indications for dialysis, the most urgent, life-threatening indications are remembered by the mnemonic AEIOU (Acidosis, Electrolytes, Intoxication, Overload, Uremia). Uremic pericarditis is a life-threatening complication of uremia that can lead to pericardial effusion and tamponade. It is an absolute and urgent indication for initiating hemodialysis.
ITE Nephrology and Hypertension Questions and Answers
A 68-year-old male in the ICU for septic shock develops a rise in serum creatinine from a baseline of 1.0 mg/dL to 3.5 mg/dL over 48 hours.
His blood pressure has required vasopressors.
A urinalysis is performed.
Which of the following findings would be most indicative of acute tubular necrosis (ATN) as the cause of his kidney injury?