Do Not Replete Calcium in Rhabdomyolysis Unless a Patient is in Tetany
Anthony D. Slonim MD, DrPH
Rhabdomyolysis is a condition that is associated with the destruction of skeletal muscle. There are a number of causes of rhabdomyolysis. These are classified as hereditary or nonhereditary. The hereditary causes of rhabdomyolysis usually involve the deficiency of a particular muscle enzyme (e.g., carnitine), which prevents the ability to generate adenosine triphosphate (ATP) by either fatty-acid oxidation or anaerobic glycolysis during exercise. These patients often have a family history of rhabdomyolysis or experience repeated bouts of rhabdomyolysis. The nonhereditary causes of rhabdomyolysis include trauma with large amounts of tissue damage (burns, crush injuries), sepsis, medications (statins, cocaine, amphetamines, anticonvulsants, serotonin, and protease inhibitors), electrolyte abnormalities (hypokalemia, hypophosphatemia), and sepsis.
The diagnosis of rhabdomyolysis usually begins with an appropriate clinical history that often includes excessive exercise associated with muscle pain and cramping. Associated symptoms are nonspecific and include nausea, weakness, and dehydration. The laboratory analysis is important in making the diagnosis. Usually, there is a metabolic acidosis, an elevated serum creatine kinase concentration >10,000 IU/L, hyperkalemia, hyperphosphatemia, and/or hypocalcemia. These abnormalities usually result from the breakdown products of the skeletal muscle. A clue to the diagnosis includes a urinalysis that will be positive for blood but will not demonstrate erythrocytes on the microscopic examination.