Cardiac
Myoglobin
Myoglobin is a small oxygen-binding haem protein found in both skeletal and cardiac muscle that leaks into the blood soon after muscle injury, including myocardial infarction. It rises early, within roughly 1 to 3 hours of cardiac injury, which historically made it useful for early rule-in work, although it is not specific to the heart.
Why it is measured
Near-patient myoglobin gives a rapid quantitative result that can support early assessment of suspected acute coronary syndrome, usually as part of a multi-marker panel alongside cardiac troponin and CK-MB rather than on its own.
| Typical range | Indicative adult range is approximately 25 to 72 ng/mL (equivalent to micrograms per litre, ug/L), with men typically slightly higher than women. Some methods quote an upper limit of around 85 to 90 ng/mL. Ranges and decision cut-offs vary by method and analyser, so always apply the assay-specific reference interval. |
|---|---|
| Sample | Whole blood or plasma, usually EDTA or lithium-heparin anticoagulated. Several closed-tube POCT systems accept the collection tube directly, so only a small venous or arterial sample is needed. |
| Turnaround | Typically around 10 to 20 minutes per sample on quantitative POCT immunoassay analysers, faster than routine central-laboratory turnaround. |
Point of care devices that report it
- Radiometer AQT90 FLEX (Myo test, time-resolved fluorescence immunoassay)
- QuidelOrtho Triage Cardiac Panel on the Triage MeterPro (fluorescence immunoassay)
- Response Biomedical RAMP Myoglobin assay (RAMP Reader)
- Boditech i-CHROMA Myoglobin (fluorescence immunoassay)
Questions, answered
Is myoglobin specific to the heart?
No. Myoglobin is present in skeletal muscle as well as cardiac muscle, so levels can rise after intense exercise, trauma, intramuscular injection, rhabdomyolysis or reduced renal clearance. It is an early but non-specific signal, so it is interpreted alongside cardiac troponin rather than used alone to confirm a cardiac cause.
Why is myoglobin used less than it once was?
High-sensitivity cardiac troponin assays now detect myocardial injury both early and with far greater cardiac specificity, so many services have moved to troponin-based pathways. Myoglobin still appears on some multi-marker POCT cardiac panels as an early-rising adjunct, but it is no longer relied on by itself.
What sample and turnaround time does POCT myoglobin need?
Most near-patient analysers use a small whole-blood or plasma sample and return a quantitative result in roughly 10 to 20 minutes. This can support faster operational decisions in the emergency department compared with sending samples to the central laboratory, which is an operational point and not a substitute for clinical assessment.