QW69-August 2026 – Nephro Critical Care Society

QW69 August 2026

Question: Select each option to validate with explanations

Clinical Case Scenario

A 50-year-old female with a history of acute myeloid leukemia (AML) was critically ill and developed a urinary tract infection caused by vancomycin-resistant Enterococcus faecium (VRE), which progressed to urosepsis. The patient had previously experienced prolonged hospitalization and had received broad-spectrum antibiotics. Initial laboratory tests revealed severe thrombocytopenia, with platelet levels measured at 20,000/µL. Due to the VRE infection, the patient was started on daptomycin therapy.

Clinical Progression Within Three Days

Creatine kinase (CK) levels increased significantly, reaching 1,000 U/L.
Serum potassium levels rose to 5.7 mmol/L.

Question: What is the most likely mechanism of this toxicity?

A. Direct nephrotoxicity causing acute tubular necrosis

B. Immune-mediated interstitial nephritis

C. Calcium-dependent pore formation in muscle cell membranes leading to rhabdomyolysis

D. Inhibition of mitochondrial oxidative phosphorylation in renal tubular cells

E. Dose-dependent suppression of bone marrow causing electrolyte imbalance

Wrong Answer: ❌ A. Direct nephrotoxicity causing acute tubular necrosis

Wrong Answer: ❌ B. Immune-mediated interstitial nephritis

Right Answer: ✅ C. Calcium-dependent pore formation in muscle cell membranes leading to rhabdomyolysis

Explanation
● Daptomycin binds to muscle cell membranes in a calcium-dependent manner.
● It inserts into the lipid bilayer, forming pores that disrupt membrane integrity.
● This causes muscle fiber necrosis → release of CK, potassium, and myoglobin.
● Hyperkalemia arises from leakage of intracellular potassium.
● Secondary AKI may occur due to myoglobinuria.

Other options:

● A (Direct nephrotoxicity): Rare, but not the primary mechanism here.
● B (Interstitial nephritis): Seen with some antibiotics (e.g., beta-lactams), not typical of daptomycin.
● D (Mitochondrial inhibition): Describes aminoglycoside toxicity, not daptomycin.
● E (Bone marrow suppression): Explains thrombocytopenia in AML, but not CK rise or hyperkalemia.

💎NephroCC Pearl

💥Daptomycin toxicity is myotoxic, not primarily nephrotoxic.
💥Always monitor CK and electrolytes during therapy, especially in critically ill patients.

Wrong Answer: ❌ D. Inhibition of mitochondrial oxidative phosphorylation in renal tubular cells

Wrong Answer: ❌ E. Dose-dependent suppression of bone marrow causing electrolyte imbalance

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