MD Renal and Urinary Systems 2 — Questions and Answers
Question 1: A patient with nephrotic syndrome has a serum albumin of 1.8 g/dL. Which complication is most directly caused by hypoalbuminemia?
- Hyperkalemia
- Edema from reduced oncotic pressure (Correct answer)
- Metabolic alkalosis
- Hypertension from sodium retention
Correct answer: Edema from reduced oncotic pressure
Hypoalbuminemia reduces plasma oncotic pressure, allowing fluid to shift into the interstitium and causing edema.
Question 2: Which enzyme converts angiotensin I to angiotensin II and is inhibited by ACE inhibitors?
- Renin
- Aldosterone synthase
- Angiotensin-converting enzyme (Correct answer)
- Neprilysin
Correct answer: Angiotensin-converting enzyme
ACE (angiotensin-converting enzyme) cleaves angiotensin I to form the vasoactive angiotensin II, and ACE inhibitors block this step.
Question 3: A 45-year-old man has recurrent calcium oxalate kidney stones. Urinalysis shows hypercalciuria with normal serum calcium. Which dietary modification is most appropriate?
- Increase dietary calcium intake (Correct answer)
- Restrict dietary calcium severely
- Increase oxalate-rich foods
- Decrease fluid intake
Correct answer: Increase dietary calcium intake
Adequate dietary calcium binds oxalate in the gut, reducing intestinal oxalate absorption and urinary oxalate excretion.
Question 4: A patient with chronic kidney disease has a GFR of 18 mL/min. Which electrolyte abnormality is most expected?
- Hypokalemia
- Hyperphosphatemia (Correct answer)
- Hypercalcemia
- Hypomagnesemia
Correct answer: Hyperphosphatemia
Reduced GFR impairs phosphate excretion, leading to hyperphosphatemia in advanced CKD.
Question 5: Podocyte injury leading to foot process effacement is the hallmark of which glomerular disease?
- IgA nephropathy
- Membranous nephropathy
- Minimal change disease (Correct answer)
- Focal segmental glomerulosclerosis
Correct answer: Minimal change disease
Minimal change disease shows diffuse podocyte foot process effacement on electron microscopy with no changes on light microscopy.
Question 6: A patient presents with flank pain, hematuria, and a palpable abdominal mass. CT reveals a large renal mass with internal fat density. What is the most likely diagnosis?
- Renal cell carcinoma
- Wilms tumor
- Angiomyolipoma (Correct answer)
- Transitional cell carcinoma
Correct answer: Angiomyolipoma
Fat density on CT is characteristic of angiomyolipoma, a benign hamartoma composed of blood vessels, smooth muscle, and fat.
Question 7: Which segment of the nephron is impermeable to water under all conditions, even in the presence of ADH?
- Descending limb of loop of Henle
- Proximal convoluted tubule
- Thick ascending limb of loop of Henle (Correct answer)
- Collecting duct
Correct answer: Thick ascending limb of loop of Henle
The thick ascending limb is constitutively impermeable to water, allowing it to dilute tubular fluid regardless of ADH levels.
MD Renal and Urinary Systems 2
A patient with nephrotic syndrome has a serum albumin of 1.8 g/dL.
Which complication is most directly caused by hypoalbuminemia?