Myoglobin is an oxygen-binding protein of skeletal muscle and heart muscle (myocardium). Its main function is to create an oxygen reserve in the muscle, which is consumed as needed to make up for temporary oxygen shortages.

Myoglobin is increased in the blood in the presence of inflammation or damage to muscle tissue, and is practically undetectable in their absence. It is not a specific marker and can be altered in a variety of pathologic conditions associated with pathology of the muscular system.

Myoglobin is filtered by the kidneys and excreted in the urine. If massive muscle damage occurs, such as from a serious injury, it begins to enter the bloodstream in large amounts and can damage the kidneys, causing acute kidney failure.