Blood and Urine Myoglobin

Blood and Urine Myoglobin: Optimal Testing Recommendations

Serum or urine myoglobin is not recommended as the primary diagnostic marker for rhabdomyolysis. Only in ambiguous cases, clinical suspicion of rhabdomyolysis can be confirmed by a positive urine or serum myoglobin test within 6 hours of symptom onset.

Guidelines for Test Utilization

• What does the test tell me?
• When should I order this test?
• When should I NOT order this test?
• How should I interpret the result?
• Is the test result diagnostic/confirmatory of the condition? If not, is there a diagnostic/confirmatory test?
• Are there factors that can affect the lab result?
• Are there considerations for special populations?
• What other test(s) might be indicated?

What does the test tell me?

Myoglobin is the first enzyme that is elevated in muscle injury, with concentrations often returning to normal in 24 hours. [back to top]

When should I order this test?

When suspecting muscle injury with these symptoms, muscle pain, dark-colored urine, fever, fatigue, nausea and vomiting, belly pain, and results from the biochemical “gold standard” for diagnosing rhabdomyolysis, creatine kinase (CK), is ambiguous, serum myoglobin test within 6 hours of the symptom onset and urine myoglobin test can provide additional evidence. [back to top]

When should I NOT order this test?

Do not order myoglobin for the evaluation of suspected acute myocardial injury. Do not order serum or urine myoglobin as the first-line test to diagnosis rhabdomyolysis. [back to top]

How should I interpret the result?

Blood myoglobin concentrations above the reference interval indicates muscle damage, but do not reveal the source or location of damage. Presence of myoglobin in urine is a strong indicator of muscle injury. Myoglobinuria is a potential risk factor of kidney injury. [back to top]

Is the test result diagnostic/confirmatory of the condition? If not, is there a diagnostic/confirmatory test?

The diagnosis of muscle injury, particularly rhabdomyolysis, requires a combination of clinical and laboratory assessment, since the classic clinical symptoms may not be present. A definitive diagnosis is often made by elevated CK and other evidence including elevated blood and urine myoglobin at the early phase of muscle injury.

CK has a half-life of more than 36 hours while myoglobin’s half life is only 2-3 hours, due to its rapid excretion and metabolism to bilirubin. Thus, serum myoglobin concentrations may return to normal within 6-8 hours after release from muscle.

Although myoglobinuria is one of the classic findings of rhabdomyolysis, urine myoglobin is not detected in >65% of patients with rhabdomyolysis due to its rapid clearance. Therefore, the absence of urine myoglobin does not exclude the diagnosis. [back to top]

Are there factors that can affect the lab result?

Serum/plasma specimens are stable at 4 degrees for one week and up to four weeks at −20 degrees. Non-hemolyzed, non-lipemic serum is preferred. Results from EDTA plasma samples are significantly lower than serum samples.

Urine samples are preferred to be collected without preservatives and assayed within 24 hours of sample collection. If the sample needs to have prolonged storage, the urine should be kept at 2 to 8 degrees and centrifuged to remove any debris before the assay. Myoglobin in urine is stable under alkaline conditions (pH 9.0) for longer days so sodium hydroxide can be added if long-term storage is needed. [back to top]

Are there considerations for special populations?

Test results may vary depending on age, gender, or health history. Results may be different depending on the lab. [back to top]

What other test(s) might be indicated?

The most reliable and sensitive indicator of muscle injury is CK, with its concentrations 5 times the upper reference range limit suggesting rhabdomyolysis. Myoglobinuria can be evaluated based on routine urine dipstick combined with microscopic examination of the urinary sediment from a fresh urine specimen. The presence of heme-positive urine in the absence of hematuria (<3 red blood cells per high-powered field) is consistent with myoglobinuria.

If complications secondary to rhabdomyolysis are concerning, or in order to identify the cause of rhabdomyolysis, these tests can be ordered:

1. Complete blood count, differential, and platelet count, for evidence of infection or hemolysis
2. Blood urea nitrogen, and creatinine, for renal function and evidence of acute kidney injury
3. Routine electrolytes plus calcium and phosphate, for hyperkalemia, hypocalcemia, and hyperphosphatemia
4. Aspartate aminotransferase and alanine aminotransferase for evidence of hepatic impairment
5. Serum albumin, for hypoalbuminemia, which can be seen with systemic capillary leak syndrome
6. Prothrombin time activated partial thromboplastin time, D-dimer, and fibrinogen, for evidence of disseminated intravascular coagulation
7. Electrocardiography, for cardiac dysrhythmias secondary to hyperkalemia and hypocalcemia
8. Blood cultures and infection work-up if febrile or suspicion for infection
9. Alcohol and toxicology screen, if suspicion for alcohol or drugs as the primary or contributing cause of rhabdomyolysis.

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References

Kodadek L, et al. Rhabdomyolysis: an American Association for the Surgery of Trauma Critical Care Committee Clinical Consensus Document. Trauma Surg Acute Care Open. 2022 Jan 27;7(1):e000836. 

Cervellin G, et al. Non-traumatic rhabdomyolysis: Background, laboratory features, and acute clinical management. Clin Biochem. 2017 Aug;50(12):656-662. 

Lappalainen H, et al. Elimination kinetics of myoglobin and creatine kinase in rhabdomyolysis: implications for follow-up. Crit Care Med. 2002 Oct. 30(10):2212-5. 

Eggers KM, et al. Diagnostic value of serial measurement of cardiac markers in patients with chest pain: limited value of adding myoglobin to troponin I for exclusion of myocardial infarction. Am Heart J. 2004;148(4):574-81.

Kavsak PA, et al. Effects of contemporary troponin assay sensitivity on the utility of the early markers myoglobin and CKMB isoforms in evaluating patients with possible acute myocardial infarction. Clin Chem Acta. 2007;380(1-2):213-6.

Last reviewed: July 2025. The content for Optimal Testing: the Association for Diagnostics & Laboratory Medicine’s (ADLM) Guide to Lab Test Utilization has been developed and approved by the Academy of Diagnostics & Laboratory Medicine and ADLM’s Science and Practice Core Committee.

As the fields of laboratory medicine and diagnostic testing continue to grow at an incredible rate, the knowledge and expertise of clinical laboratory professionals is essential to ensure that patients receive the highest quality and most useful laboratory tests. ADLM’s Academy and Science and Practice Core Committee have developed a test utilization resource focusing on commonly misused tests in hospitals and clinics. Improper test utilization can result in poor patient outcomes and waste in the healthcare system. This important resource geared toward medical professionals recommends better tests and diagnostic practices. Always consult your laboratory director to make sure these recommendations are appropriate for your patient population.