COMSAE Renal and Urinary Systems 1 — Questions and Answers
Question 1: A patient with chronic kidney disease has a GFR of 22 mL/min/1.73 m². According to KDIGO staging, what CKD stage is this?
- Stage 2
- Stage 3b
- Stage 4 (Correct answer)
- Stage 5
Correct answer: Stage 4
KDIGO defines CKD Stage 4 as GFR 15–29 mL/min/1.73 m², which corresponds to severely decreased kidney function.
Question 2: Which urinalysis finding is most characteristic of nephrotic syndrome?
- RBC casts
- Massive proteinuria (>3.5 g/day) (Correct answer)
- WBC casts
- Hematuria with dysmorphic RBCs
Correct answer: Massive proteinuria (>3.5 g/day)
Nephrotic syndrome is defined by proteinuria >3.5 g/day, hypoalbuminemia, edema, and hyperlipidemia.
Question 3: A patient presents with oliguria, flank pain, and hematuria after starting an NSAID. Urinalysis shows muddy brown casts and elevated BUN/creatinine. What type of acute kidney injury is this?
- Prerenal AKI
- Intrinsic renal AKI (ATN) (Correct answer)
- Postrenal AKI
- Interstitial nephritis
Correct answer: Intrinsic renal AKI (ATN)
NSAIDs reduce prostaglandin-mediated afferent arteriole dilation, causing ischemia and acute tubular necrosis, characterized by muddy brown granular casts.
Question 4: Which feature best distinguishes prerenal AKI from intrinsic renal AKI?
- BUN:creatinine ratio >20:1 and FeNa <1% (Correct answer)
- FeNa >2% and muddy brown casts
- Proteinuria >3.5 g/day
- Eosinophiluria on urinalysis
Correct answer: BUN:creatinine ratio >20:1 and FeNa <1%
In prerenal AKI the tubules are intact so they avidly reabsorb sodium (FeNa <1%) and urea, raising the BUN:creatinine ratio above 20:1.
Question 5: The sympathetic nervous system innervates the kidney via which spinal levels, relevant to osteopathic viscerosomatic reflexes?
- C1–C4
- T10–L1 (Correct answer)
- L2–L4
- S2–S4
Correct answer: T10–L1
Renal sympathetic innervation originates from T10–L1, and somatic dysfunction at these levels can reflect renal pathology through viscerosomatic reflex arcs.
Question 6: Which diuretic class acts on the thick ascending limb of the loop of Henle and is most potent for volume removal in acute pulmonary edema?
- Thiazide diuretics
- Potassium-sparing diuretics
- Loop diuretics (Correct answer)
- Osmotic diuretics
Correct answer: Loop diuretics
Loop diuretics (e.g., furosemide) inhibit the Na-K-2Cl cotransporter in the thick ascending loop, producing the greatest diuresis of any diuretic class.
COMSAE Renal and Urinary Systems 1
A patient with chronic kidney disease has a GFR of 22 mL/min/1.73 m².
According to KDIGO staging, what CKD stage is this?