Rhabdomyolysis (we say “Rhabdo” for short) is a rare condition involving breakdown of muscle. It can be life-threatening as muscle products clog the kidneys, requiring dialysis that’s sometimes permanent. Rhabdo can occur from severe crush injury of a single arm or leg, or can be due to diseases that affect many muscles. The latter situation may be subtle.
Crush trauma that causes Rhabdo may be obvious (trapped under a car), but can also happen if stuck in a single position for a long time (including coma or surgery). It can occur with severe muscle exertion, like struggling a long time while restrained, agitation from psychosis or amphetamine overdose, ongoing seizures, and in untrained long-distance runners in the heat (sickle cell trait increases the risk).
Medications that cause Rhabdo include statins to lower cholesterol, and anti-psychotics, among others. A particular danger occurs from interactions between drugs, especially when a new brief course of the antibiotic clarithromycin is given (commonly for a certain stomach bacteria), without stopping the cholesterol medication. Various poisons, infections, and diseases are occasionally responsible.
If Rhabdo is widespread, a patient may feel generalized pain and achiness, usually in the shoulders, thighs, and back. If severe, there may be fever, nausea, and abdominal pain. Muscles are usually at least somewhat tender or uncomfortable when pressed on. Urine turns reddish-brown from muscle pigment in half of patients.
Diagnosis is easily made by a blood test for the muscle enzyme creatine kinase (CK) [also called creatine phosphokinase (CPK)]. A slightly high value doesn’t count; it’s usually at least 10-times normal, and may even be 110-times. The CK is not part of a routine blood chemistry panel, but liver enzymes ALT and AST are, and would be high because they’re also present in muscle. While waiting for blood test results, we might have a clue if dipstick urinalysis done on the spot shows “blood,” because muscle pigment makes the test positive.
Treatment is mainly giving lots of IV fluids to flush out the muscle pigment, and of course treating the original cause. patients are usually hospitalized, and frequent checks are done on blood levels of potassium, phosphorus, and calcium. Some patients may need dialysis, which will hopefully only be temporary.