CK & rhabdomyolysis
What it means
Creatine kinase (normal ~25–200 U/L) rises with muscle injury. Rhabdomyolysis = CK >1000 (usually >5000, can reach tens of thousands) — crush/long-lie, seizures, statins, extreme exertion, ischaemia. Myoglobin release → pigment (myoglobinuric) AKI plus hyperkalaemia, hyperphosphataemia, hypocalcaemia; treat with aggressive IV fluids. A CK in the hundreds is NOT rhabdomyolysis.
Worked example
Trapped 12 h, CK 840 with a rising urea/creatinine → the AKI is HYPOVOLAEMIC/pre-renal; CK 840 is far too low for rhabdomyolysis.
In the exam
A man trapped for 12 hours without water is hypotensive with a raised urea and creatinine and a CK of 840 U/L.
What settles it
Rhabdomyolysis needs CK in the thousands (>1000, usually >5000); a mildly raised CK with AKI after dehydration = pre-renal/hypovolaemic AKI.
Classically confused with
AKI — pre-renal, renal or post-renal
Source: StatPearls — Rhabdomyolysis