Hypothyroid myopathy with periodic paralysis as the main symptom: a case report and literature review.

Hypothyroid myopathy is a skeletal muscle disease caused by hypothyroidism. However, patients with hypothyroidism are often misdiagnosed as polymyositis if they do not have a clear history of thyroid gland or obvious hypometabolic symptoms, but with myasthenia and myalgia as the main symptoms or the first symptoms. Moreover, hypothyroid myopathy with periodic paralysis as the first symptom is rare in clinic. In this study, we summarized the clinical data of 1 case of hypothyroid myopathy with periodic paralysis as the first symptom in our clinical diagnosis and treatment. A 27-year-old male patient with recurrent periodic paralysis was found with hypothyroidism during a most recent attack of myasthenia and was diagnosed with hypothyroid myopathy, which was relieved after oral administration of levothyroxine. We also found 13 similar cases reported internationally, and summarized their clinical characteristics, diagnosis, and treatment methods to provide reference for the clinical diagnosis and treatment of such cases. In general, periodic paralysis may be the main symptom or even the first symptom of hypothyroid myopathy, which is easy to be confused with renal tubular acidosis (RTA) or other autoimmune diseases. The diagnosis is mainly based on the detection of thyroid function and thyroid autoantibodies. Timely supplement of thyroxine and correction of electrolyte disorders are the key to treatment.