MD Renal and Urinary Systems 5

Question 1

A patient with multiple myeloma develops acute kidney injury. Light chain casts in tubules are noted on biopsy. What is this condition called?

Accepted Answer

Cast nephropathy (myeloma kidney)

Answer

Cast nephropathy (myeloma kidney) occurs when monoclonal light chains precipitate with Tamm-Horsfall protein in tubules, causing obstruction and AKI.

Question 2

A patient on tacrolimus after a renal transplant develops a rising creatinine. Biopsy shows tubular vacuolization and arteriolar hyalinosis. What is the cause?

Accepted Answer

Calcineurin inhibitor nephrotoxicity

Answer

Calcineurin inhibitors (tacrolimus, cyclosporine) cause nephrotoxicity manifesting as tubular vacuolization and arteriolar hyalinosis on biopsy.

Question 3

Which glomerular disease is associated with Heymann nephritis in rats and is the most common cause of nephrotic syndrome in adults?

Accepted Answer

Membranous nephropathy

Answer

Membranous nephropathy, caused by anti-PLA2R antibodies forming subepithelial immune complexes, is the leading cause of nephrotic syndrome in non-diabetic adults.

Question 4

A patient has metabolic acidosis with a normal anion gap, hyperchloremia, and urine pH persistently above 5.5 despite acidemia. Which type of RTA is this?

Accepted Answer

Type I (distal) RTA

Answer

Type I (distal) RTA is characterized by inability to acidify urine (pH >5.5) due to defective H+ secretion in the collecting duct, causing hyperchloremic metabolic acidosis.

Question 5

Free water clearance (CH2O) is negative in a patient. What does this indicate?

Accepted Answer

Patient is excreting concentrated urine and retaining free water

Answer

Negative free water clearance means the kidney is excreting urine more concentrated than plasma, retaining free water (as in SIADH or normal ADH response to dehydration).

MD - Doctor of Medicine Practice Test

MD - Doctor of Medicine Practice Test

MD Renal and Urinary Systems 5