Endocrine Abstracts

Introduction: Hypothyroid myopathy with moderate elevation of muscle enzymes is not uncommon. However rhabdomyolysis and acute renal failure due hypothyroidism is rare and only few cases have reported. We describe a patient with rhabdomyolysis due to primary hypothyroidism.

Case report: A 45-year-old male was admitted with 6 weeks history of generalised muscle weakness. He described his gait as ‘walking like a drunk’ in the absence of alcohol. He also complained of poor appetite and weight gain. His wife noticed that he was mentally slow and turned pale. On examination he had dry skin, bradycardia, peri-orbital oedema and slow relaxing reflexes with proximal myopathy. Investigations revealed normal liver functions renal failure and raised muscle enzymes. The final diagnosis was Rhabdomyolysis secondary to hypothyroidism. He was treated with levothyroxine and his general condition improved along with biochemical parameters.

Discussion: Rhabdomyolysis is defined by creatinine kinase levels of more than ten times the upper limit of normal and elevated plasma creatinine, usually associated with myoglobinuria. Hypothyroidism causing rhabdomyolysis is rare and the exact mechanism remains unclear. Various hypothesis including impaired mitochondrial oxidative metabolism, induction of insulin resistant state and decreased muscle carnitine levels have been proposed. Statin therapy, advancing age, diabetes mellitus, liver disease, renal impairment, alcoholism, are additional risk factors associated with myopathy. Our case is interesting as rhabdomyolysis is the first manifestation of hypothyroidism and no additional risk factors have been demonstrated. Thyroid hormone replacement usually reverses the rhabdomyolysis and improves the thyroid and renal functions as seen in our case.

Conclusion: Hypothyroidism, although rare, should be considered as a potential cause in patients presenting with elevated muscle enzymes and acute renal failure.