Hypothyroidism simulating as polymyositis

Polymyositis-like syndrome in hypothyroidism is a rare condition characterised by proximal muscle weakness and elevated muscle enzymes. Patients with this condition can initially be misdiagnosed as having polymyositis due to similar characteristics of both diseases; however a response to thyroxine is the main differentiating feature. This report highlights the case of a 30-year-old male who had severe myalgia and proximal muscle weakness. In addition to raised creatinine phosphokinase (CPK) levels, his biochemical profile showed hypothyroidism. Initially thought to be suffering from polymyositis, improvement in both clinical and biochemical profile with thyroxine led to the diagnosis of polymyositis-like syndrome associated with hypothyroidism.