Endocrine Abstracts

Patients with clinical hypothyroidism often complain of muscular symptoms i.e., cramps, weakness and fatigue. However, rhabdomyolysis triggered by severe hypothyroidism is rarely reported. In most cases, external triggers (use of statins or excessive exercise) can be easily identified and modified. In absence of beforementioned triggers, it is prudent to look for other causes of rhabdomyolysis. On the forefront, it would be crucial to exclude myocardial ischaemia, followed by inflammatory myopathies, use of illicit drugs, electrolyte abnormalities, seizure, trauma, and finally hypothyroidism. We report a case of 40-year man, an avid gym enthusiast, who presented to GP Assessment Unit at the Leicester Royal Infirmary with tiredness and myalgia. His blood work showed acute kidney injury stage 2 with creatinine kinase readings of 14599 IU/l. It was assumed rhabdomyolysis was related to strenuous exercise as patient was known to exercise daily. He was commenced on intravenous fluids and admitted onto an acute medical unit. His ECG showed normal sinus rhythm with no evidence of ischaemia. Upon further questioning, it became apparent that patient has stopped going to the gym 6 weeks prior due excessive tiredness and proximal muscle weakness. Further labs were ordered which revealed TSH >150 mIU/l, with free thyroxine (T4) of 2.6 mIU/l, and thyroid peroxidase antibody of 455 mIU/l. Subsequently, patient was commenced on 75 mg of levothyroxine along with intravenous fluids for the duration of 48 h. On 3 monthly follow up, labs showed TSH of 0.24 mIU/l, free thyroxine (T4) of 25.4mIU/l and creatinine kinase of 230IU/l. In addition, patient reported near complete resolution of myalgia and proximal weakness. This case illustrates the importance of screening for hypothyroidism in patients with rhabdomyolysis and no other plausible etiologies.