Rhabdomyolysis is a disorder caused when damaged muscle releases toxic substances such as creatine kinase (CK) and myoglobin into the bloodstream. The main associated risk factors are alcoholism, lesions caused by compression, overexertion, heat intolerance, sunstroke, low phosphate levels, convulsions and drug use or overdose. Drugs commonly involved are cocaine, amphetamines, statins and heroin.
We present the case of a male patient aged 41 years who was transported to the emergency department due to reduced consciousness after falling at home. His medical history included hepatitis C, paranoid schizophrenia and habitual use of heroin. In the 72 hours prior to admission, he began to experience muscle weakness and widespread myalgia, which coincided with starting a methadone rehabilitation programme. In the 24 hours before admission, he also experienced headache, nausea, vomiting and a fever of 39.5ºC.
Physical examination showed drowsiness, lack of awareness of surroundings, hypotension (70/30mm Hg), 72% baseline oxygen saturation and signs of mucocutaneous dehydration. The examination revealed no other significant abnormalities. The blood count and biochemical test results were as follows: pH 7.10; PCO2 23mm Hg; HCO3 16mEq/l; haemoglobin 15.5mg/dl; leukocytes 23×103/uL (88% neutrophils); C-reactive protein (CRP) 10mg/dl; creatinine 2.88mg/dl; potassium 6.6mEq/l; alanine aminotransferase 160IU/l; aspartate aminotransferase 523IU/l; phosphorus 7.0mg/dl; CPK 86 000IU/l. Neurological disorders were ruled out by a cranial CT and lumbar puncture. In subsequent hours, renal function deteriorated until serum creatinine reached 11.4mg/dl. Volume replacement therapy was initiated, which resulted in significant positive balances and urine production; renal function improved continuously over the following days. Haemodialysis was not required. Upon discharge, the patient’s creatinine level was 2.1mg/dl, but he was lost to follow-up.
Acute renal failure is the most severe complication of rhabdomyolysis, whose prognosis depends on the degree to which renal function is compromised. It often presents with high CPK levels, hypercalcaemia, hyperphosphataemia and high anion gap metabolic acidosis. Our patient experienced all of these disorders. “Hard” drugs such as heroin and cocaine are classically associated with rhabdomyolysis. It is widely demonstrated that narcotics lead to rhabdomyolysis, which causes acute renal failure due to tubular obstruction arising when myoglobin leaks into the kidney.1
Mechanisms associated with the development of rhabdomyolysis in cases of drug abuse are decreased level of consciousness, coma or prolonged immobilisation being the main cause. Prolonged compression of muscles leads to ischaemia, which in turn triggers rhabdomyolysis. On the other hand, the direct manner in which methadone leads to rhabdomyolysis seems to arise from an increase in the muscle's demand for oxygen, which augments the state of muscle ischaemia.1,2
Most of the cases described are associated with abuse of multiple substances, such as heroin, cocaine, benzodiazepines or alcohol.3,4 However, our case is an interesting one, since few articles describe rhabdomyolysis and acute renal failure caused by methadone abuse.1,5
Conflicts of interest
The authors affirm that they have no conflicts of interest related to the content of this article.
