Rhabdomyolysis and Myoglobinuria

Snake venom contains toxins called myotoxins that affect the muscle cells causing Rhabdomyolysis and Myoglobinuria.

Myoglobinuria: is when myoglobin is excreted in the urine causing tea-like discolouration of the urine. Is associated with rhabdomyolysis and may be indicative of renal damage.

Rhabdomyolysis:

-is the breakdown of muscle fibres
-causes release of potentially toxic cellular components into circulation - includes creatinine kinase, myoglobin and potassium
-may have consequences such as hyperkalemia (release of potassium into circulation - can cause life threatening dysrhythmias and death), acute renal failure in 30% patients(from precipitation of myoglobin causing tubule blockage and/or by direct nephrotoxic effects of myglobin), hypervolemia (decrease in blood plasma volume), metabolic acidosis
-symptoms may include fever, muscle pain and/or weakness

Causes (are many):
-trauma -exercise induced -toxicologic (includes many drugs and venoms) -environmental
and many more.

Diagnosis:
-Lab studies: most useful diagnostic measure is serum creatinine kinase (CK) levels (although CK may be released into the blood stream in patients with other disorders eg acute myocardial infarction) therefore CK levels are a good but not entirely specific marker
-Urine dipstick test: may reveal the presence of myoglobin in the urine which is a definitive marker of rhadomyolysis however this is only present in about 50% of patients
-Blood tests for other markers eg elevated potassium levels

Treatment:
-treatment of underlying condition eg snake toxins
-fluid replacment - saline
-potassium may need correcting
-alkaline diuresis may prevent renal damage