How is rhabdomyolysis diagnosed?

• A. An elevated level of creatine kinase (CK) in the blood, since CK is easier to measure than myoglobin and serves as a marker, though myoglobin does the damage.
• B. Presence of dark urine only; no blood tests.
• C. MRI showing brain lesions.
• D. Elevated liver enzymes.

Answer: (A)

Rhabdomyolysis is diagnosed primarily by confirming muscle injury through a markedly elevated creatine kinase (CK) level in the blood. CK rises when skeletal muscle fibers are damaged, and its level correlates with the extent of injury and the risk of kidney damage from released myoglobin. Myoglobin contributes to kidney injury but is not as reliably measured or used for diagnosis as CK, so relying on dark urine or urine findings alone isn’t sufficient. MRI showing brain lesions or elevated liver enzymes can occur in other contexts and aren’t diagnostic for rhabdomyolysis. So, the clearest and most practical diagnostic marker is a high CK level in the blood.