Rhabdomyolysis

Rhabdomyolysis is the breakdown of muscle fibers resulting in the release of muscle fiber contents (myoglobin) into the bloodstream. Some of these are harmful to the kidney and frequently result in kidney damage.

When muscle is damaged, a protein pigment called myoglobin is released into the bloodstream and filtered out of the body by the kidneys. Myoglobin breaks down into potentially harmful compounds. It may block the structures of the kidney, causing damage such as acute tubular necrosis or kidney failure.

Dead muscle tissue may cause a large amount of fluid to move from the blood into the muscle, reducing the fluid volume of the body and leading to shock and reduced blood flow to the kidneys. The disorder may be caused by any condition that results in damage to skeletal muscle, especially trauma.

Causes of Rhabdomyolysis

Muscular trauma is the most common cause of rhabdomyolysis. Less common causes include muscle enzyme deficiencies (e.g. carnitine) or glycogen storage diseases. Patients affected by rhabdomyolysis often have a familial history of rhabdomyolysis or experience repeated bouts of the disease.

The main hereditary causes of rhabdomyolysis are due to inborn errors of metabolism affecting carbohydrate and fat metabolism within the muscle. Hereditary causes of rhabdomyolysis are often precipitated by brief, intense exercise or fasting. Extreme muscle exertion, even in well-conditioned individuals, may cause rhabdomyolysis.

The nonhereditary causes of rhabdomyolysis include large amounts of tissue damage (burns, crush injuries) sepsis, medications, electrolyte abnormalities (hypokalemia, hypophosphatemia), sepsis and snake and insect venoms. Rhabdomyolysis also can develop as a complication of babesiosis, as a result of potassium deficiency or heat stroke, but the most frequent cause is crush injuries. Malignant hyperthermia is a rare cause of rhabdomyolysis associated with certain types of inhaled anesthetics.

Signs of Rhabdomyolysis

Weakness, muscle pain and tea-colored urine are the main clinical manifestations. Often human patients and animals are unwilling or unable to move due to severe pain. Vomiting is often present. A drop in urine output is a sign of impending kidney failure.

Exertional rhabdomyolysis (ER) is common in sled dogs, animals with high energy expenditures that consume high fat (60% of ingested calories) diets.[1] Exertional rhabdomyolysis develops more often in dogs that retire during the initial 500 miles of a long-distance race, compared with dogs that complete the race [2].

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Treatment of Rhabdomyolysis

The treatment is focused on removing the offending agent and supportive care. One of the major consequences of rhabdomyolysis is acute renal failure, and the treatment of this syndrome is directed at preventing this complication. Aggressive intravenous hydration is indicated to improve the solubility of by-products and urine flow.[4]

Rhabdomyolysis is a potentially life-threatening condition that must be suspected in all patients with a history of any circumstance that can result in damage of skeletal muscle. Rhabdomyolysis is very common and may result from primary muscle disease or from many systemic diseases that incidentally affect skeletal muscles.

References:
1. Piercy RJ, Hinchcliff KW, Morley PS, DiSilvestro RA, Reinhart GA, Nelson SL Jr, Schmidt KE, Craig AM. Vitamin E and exertional rhabdomyolysis during endurance sled dog racing. Neuromuscul Disord. 2001 Apr;11(3):278-86.
2. Hinchcliff KW, Shaw LC, Vukich NS, Schmidt KE. Effect of distance traveled and speed of racing on body weight and serum enzyme activity of sled dogs competing in a long-distance race. J Am Vet Med Assoc. 1998 Sep 1;213(5):639-44.
3. Jacobson LS, Lobetti RG. Rhabdomyolysis as a complication of canine babesiosis. Small Anim Pract. 1996 Jun;37(6):286-91.
4. Lisa Marcucci, Elizabeth A Martinez. Avoiding Common ICU Errors

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