Rhabdomyolysis describes the injury and breakdown of voluntary muscles, also known as skeletal muscles. The contents of the destroyed cells enter the circulation, causing metabolic disturbances throughout the body. Rhabdomyolysis most commonly occurs due to crush injury of the muscles, electrical shock injury, lack of blood supply to the muscles, marked overexertion, alcohol abuse, an adverse reaction to medication or chemical poisoning. Complications of rhabdomyolysis can occur early or late in the progression of the disorder.
Hyperkalemia
Muscle cells contain a high concentration of potassium. Muscle breakdown can cause markedly elevated blood potassium, or hyperkalemia. The degree of elevation correlates to the extent of muscle injury. The University of Maryland Medical Center notes that mild hyperkalemia may not cause symptoms. As the potassium level increases, symptoms are more likely to appear, including numbness or tingling, breathing difficulty, fatigue, muscle weakness or paralysis and nausea and vomiting. The most life-threatening adverse effects of hyperkalemia are heart rhythm and function disturbances. Elevated blood potassium can disrupt the heart's electrical conduction system. Abnormal, life-threatening heart rhythms may develop. Hyperkalemia may also interfere with heart muscle function, potentially causing heart failure.
Hypocalcemia
Muscle cell breakdown precipitates a rapid decrease in circulating blood calcium, or hypocalcemia. The Cleveland Clinic explains that a sudden decrease in blood calcium adversely affects nerves throughout the body, potentially triggering a variety of symptoms. Possible manifestations of hypocalcemia include tingling, numbness, and muscle spasms, twitching and cramps. Cramps affecting the throat or chest muscles can cause breathing difficulties and respiratory distress. Hypocalcemia may also adversely affect the muscular function of the heart, potentially contributing to heart failure.
Liver Malfunction
In a review article published in "American Family Physician," Dr. John Sauret and colleagues report that approximately one-quarter of patients with rhabdomyolysis experience liver malfunction in the early stages of the disorder. The authors explain that enzymes released from damaged muscle cells may trigger liver inflammation and injury.
Acute Kidney Failure
Muscle cells contain a high concentration of the oxygen-binding protein myoglobin, which enters the circulation during rhabdomyolysis. The kidneys filter myoglobin and excrete it in the urine. High levels of urinary myoglobin, however, damage the kidneys. Direct kidney cell injury occurs due to myoglobin exposure. The protein can also cause physical obstruction of the filtering units of the kidneys, limiting overall kidney function. Extensive myoglobin-induced kidney damage can lead to acute kidney failure, a late complication of rhabdomyolysis. Sauret and colleagues report that myoglobinuria provokes acute renal failure in up to 15 percent of those with rhabdomyolysis. The risk for acute renal failure increases in parallel with the extent of muscle breakdown. Aggressive treatment can potentially limit kidney damage due to myoglobinuria.
References
- University of Maryland Medical Center: Rhabdomyolysis
- Washington University, Neuromuscular Disease Center: Myoglobinuria--Rhabdomyolysis
- "American Academy of Family Physicians"; Rhabdomyolysis; John M. Sauret, M.D., et al.; March 2002
- Medline Plus: Rhabdomyolysis
- University of Maryland Medical Center: Hyperkalemia
