Endocrine Abstracts

We present a case of a 65-year-old man who arrived at the emergency department after falling and lying for a long time at home. Relevant past medical history includes asthma, previous myocardial infarction, rheumatoid arthritis, and hypertension. Biochemically, he had a creatine kinase (CK) of 7461, normal renal function, and deranged thyroid function with a thyroid stimulating hormone (TSH) of 95.9 and thyroxine (T4) of 9. Subsequently, the patient was treated for a long lie causing high CK with aggressive intravenous crystalloids. Patient was then referred to rheumatology for possible polymyositis given persistently raised CK despite fluids and absence of dermatological lesions. Myositis screen requested, and it was negative. However, an MRI of the hip and femur revealed possible diffuse myositis. We requested an EMG and excluded polymyositis. Given the absence of polymyositis and deranged thyroid function tests, another possible diagnosis of thyroid myopathy emerged. Further immunological tests revealed positive thyroid peroxidase and negative rheumatoid factor. The patient’s CK levels continue to deteriorate, reaching a level above 10,000. After consulting with the endocrinology team, they started the patient on a low dose of Levothyroxine. After a week of levothyroxine, the patient’s CK levels improved dramatically to 4000 from 10,000. The dose of levothyroxine was then doubled on discharge, and the CK levels were subsequently normalised. Rhabdomyolysis brought on by hypothyroidism is a recognised but rare condition. Very few cases of hypothyroidism causing rhabdomyolysis have been reported in the literature. The pathophysiology of rhabdomyolysis in hypothyroidism remains unclear, and various hypotheses have been postulated. Screening for hypothyroidism in patients with elevated muscle enzymes should be considered, since an early diagnosis and prompt treatment of hypothyroidism are essential to prevent rhabdomyolysis and its consequences.