A myoglobin test measures the amount of myoglobin, a protein found in your skeletal muscles (the muscles attached to your tendons and bones) and heart muscles, in your blood or urine (pee).
Healthcare providers may use a myoglobin blood test to detect muscle damage. When your heart or skeletal muscles experience an injury, your muscle cells release myoglobin into your bloodstream. The level of myoglobin in your blood can rise very quickly with severe muscle damage, and healthcare providers typically measure it within a few hours following an injury.
Your kidneys filter out myoglobin from your blood and release it into your urine. Healthcare providers sometimes use a urine test to evaluate myoglobin levels if you’ve had extensive damage to your skeletal muscles (rhabdomyolysis). Urine myoglobin levels reflect the degree of muscle injury — the more myoglobin in your urine, the more severe the injury. Since myoglobin is toxic to your kidneys, a urine test can also assess the risk of kidney damage.
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Myoglobin is a protein that’s found in your striated muscles, which includes skeletal muscles (the muscles attached to your bones and tendons) and heart muscles. Its main function is to supply oxygen to the cells in your muscles (myocytes).
All cells in your body need oxygen in order to function. They use oxygen to convert stored energy. Your skeletal muscles and heart muscles require a lot of oxygen and energy due to their constant use.
While both myoglobin and hemoglobin are responsible for carrying oxygen to certain tissues, they have different functions.
Hemoglobin is a protein found in red blood cells that gives those cells their red color. Its main function is to carry oxygen from your lungs to the rest of the cells in the tissues and organs of your body.
Myoglobin is mainly present in your striated muscles (the kind of muscles that you consciously move, like your arm and leg muscles), whereas hemoglobin is found in your bloodstream. Myoglobin only enters your bloodstream if you experience muscle damage. Like hemoglobin, myoglobin is the reason your muscle tissues have a reddish hue.
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Your healthcare provider may order a myoglobin blood test if you’re experiencing symptoms of severe damage to your muscles, such as from accidents that result in muscle trauma, or muscular dystrophy.
Symptoms of muscle injury or damage include:
While healthcare providers have used myoglobin blood tests along with troponin tests to help detect a heart attack early in the past, they now use myoglobin testing less frequently for this purpose. More recent studies have revealed that newer markers, such as troponin, are better for detecting heart attacks.
Your healthcare provider may order a urine myoglobin test if you have extensive damage to your skeletal muscles, resulting in the rapid breakdown of muscle (rhabdomyolysis), and if they suspect that you may have damage to your kidneys from excess myoglobin.
Your healthcare provider may also order either test if you have acute kidney failure without any clear cause.