Diagnostic Use
Plasma myoglobin may be increased in any condition which causes muscle cell injury, including myocardial infarction and skeletal muscle damage. Myoglobin is rapidly cleared from the serum in acute conditions.
Myoglobin is a non-specific cardiac marker which starts to rise in 2 – 4 hours after myocardial infarction, peaks at 4 – 12 hours, and generally returns to normal in 15 – 40 hours. It is therefore useful as an early, non-specific marker, to rule out MI, provided that the specimen is collected within the appropriate time frame. Its rapid return to normal makes it suitable as a marker of re-infarction at a time when the other cardiac markers are still elevated.
Time Course for Myocardial Infarction Markers
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starts to rise
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Peak
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remains elevated
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Myoglobin
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2-4h
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4-12h
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15-40h
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Troponin T
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4-6h
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12-24h
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4-10d
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Total CK and CKMB
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4-6h
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24-48h
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3-5d
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Acute rhabdomyolysis
Myoglobin is one of the pathogenic factors for acute renal failure. Myoglobin typically peaks earlier than creatine kinase (CK) by around 0.5-1 day. Its elimination from circulation is quicker than CK – with cessation of further muscle damage, the elimination half-life is around 12 – 24 hours (the t 1/2 for CK is around 26-36hours). Although myoglobin can be detected in urine in rhabdomyolysis, as myoglobin is predominantly metabolised by the reticulo-endothelial system, even an oliguric-anuric state does not significantly prolong its plasma elimination time.
Raised plasma myoglobin level is a better predictive marker for acute renal failure than CK or urine myoglobin level. In the setting of rhabdomyolysis, the risk of acute renal failure becomes significant when the plasma myoglobin peak is >5,300ug/L and risk will rise substantially if peak myoglobin is >8,000ug/L. Note that other factors like hypotension, hypovolaemia, and electrolyte disturbances will also contribute to risk for acute renal failure independently of the myoglobin level.
References
1. Lappalainen H et al Elimination kinetics of myoglobin and creatine kinase in rhabdomyolysis: Implications for follow up Crit Care Med 2002; 30(10): 2212-15
2. Mikkelsen TS et al Prognostic value, kinetics and effect of CVVHDF on serum of the myoglobin and creatine kinase in critically ill patients with rhabdomyolysis. Acta Anaesthesiol Scand 2005; 49:859-864
See also
- Troponin T
- Urine Myoglobin
Test Method
Test performed by: LabPlus Automation
Principle: Sandwich type immunoassay with chemiluminescence detection
Reagents: Roche Assay
Analyser: Roche Cobas