Which laboratory value requires monitoring due to risk of rhabdomyolysis?

Rhabdomyolysis involves the rapid breakdown of striated muscle, releasing intracellular contents into the systemic circulation. This necrosis results in the leakage of myoglobin and enzymes, leading to tubular obstruction and severe nephrotoxicity, which can culminate in acute renal failure if not treated aggressively. Rationale: A. Hemoglobin levels indicate the oxygen-carrying capacity of blood. A value of 11.2 g/dL is slightly below reference ranges but is not a diagnostic marker for muscle necrosis. Monitoring Hgb helps identify anemia or blood loss, but it lacks the tissue specificity required to assess or manage active skeletal muscle breakdown. B. A platelet count of 250,000/mm³ falls within the standard physiological range of 150,000 to 400,000/mm³. Extreme rhabdomyolysis can trigger disseminated intravascular coagulation, but this normal value does not indicate myocyte injury or provide information regarding the risk of renal complications from released muscle proteins. C. Sodium at 139 mEq/L is a normal finding, reflecting stable osmolality and fluid balance. Electrolyte imbalances like hyperkalemia or hyperphosphatemia are common in muscle lysis, but a stable sodium level does not serve as a clinical indicator for the presence or severity of rhabdomyolysis-induced tissue damage. D. Creatine kinase (CK) is the primary biomarker for muscle injury, with levels >5 times the upper limit indicating rhabdomyolysis. Elevated CK levels reflect the magnitude of muscle fiber destruction and are used to gauge the risk of myoglobin-induced acute kidney injury.