Muscle Injury

Rhabdomyolysis is caused by muscle injury. Regardless of the mechanism, the muscle injury sets in motion a cascade of events that leads to leakage of extracellular calcium ions into the intracellular space.

The excess calcium ions lead to a pathological interaction of actin and myosin. This in turn activates cellular proteases and these cause destruction and necrosis of muscle.

The calcium ions released in the cytosol lead to cell permeability and capillary leakage. Membrane pumps such as Sodium Potassium ATPase (Na K ATPase) are damaged by toxins, exercise and muscle compression.

Large quantities of potassium, myoglobin, phosphate, CK and urate leak into the extracellular space and circulation. In addition, muscle cell hypoxia depletes levels of Adenosine Triphosphate (ATP).

This has an effect on the renal system and if the renal threshold is exceeded, myoglobin (a dark red protein) appears in the urine.