In rhabdomyolysis, which laboratory abnormality is most characteristic?

In rhabdomyolysis, which laboratory abnormality is most characteristic?

• A. ALT elevation
• B. LDH elevation
• C. Hyperkalemia
• D. CPK > 20,000

Answer: (D)

Rhabdomyolysis causes massive skeletal muscle breakdown, so the most telling lab sign is an enormous rise in creatine phosphokinase, reflecting the extent of muscle injury. CK is highly specific to muscle, so when levels skyrocket—often into tens of thousands of units per liter—it points to muscle damage rather than liver or other tissues. Other abnormalities like ALT and LDH can be elevated too, but they’re less specific to muscle injury. Hyperkalemia can occur because potassium is released from damaged cells, but its presence isn’t as diagnostic as a dramatic CK elevation. So, a very high CK level is the hallmark finding.

Rhabdomyolysis causes massive skeletal muscle breakdown, so the most telling lab sign is an enormous rise in creatine phosphokinase, reflecting the extent of muscle injury. CK is highly specific to muscle, so when levels skyrocket—often into tens of thousands of units per liter—it points to muscle damage rather than liver or other tissues. Other abnormalities like ALT and LDH can be elevated too, but they’re less specific to muscle injury. Hyperkalemia can occur because potassium is released from damaged cells, but its presence isn’t as diagnostic as a dramatic CK elevation. So, a very high CK level is the hallmark finding.