Myoglobin
Myoglobin is a protein that stores oxygen inside muscle cells, including heart muscle. When muscle is damaged, myoglobin is released into the blood and can be measured.
Myoglobin rises quickly after muscle injury, so it has been used as an early, though non-specific, signal of muscle or heart-muscle damage. It can also reflect how the muscles and kidneys are being affected in certain conditions. It is typically used in a clinical context alongside more specific tests.
A high myoglobin indicates muscle breakdown, which can result from heart-muscle injury, skeletal muscle damage, intense exercise, or trauma. Because it is non-specific and often an acute test, it is interpreted with troponin and your clinical picture. Very high levels can also matter for kidney function, which your clinician will consider.
A low or normal myoglobin generally suggests no significant recent muscle breakdown. This is typically reassuring.
A value within the normal range is expected when there is no significant muscle injury. Recent strenuous exercise can raise it, so your clinician will interpret it in context.
Sources
Educational context only, not medical advice or a diagnosis. Reference ranges vary by lab, age and sex; always discuss your results with a clinician.