Severe hyperthyroidism, along with several other endocrinopathies, is well recognised as a cause of myopathy. This myopathic clinical picture varies from mild myasthenia to profound muscular weakness. We present the case of a 61 year old female (Ms SM), with learning difficulties, who presented with a short history of reduced mobility and anorexia. She was noted to have hypernatraemia and acute kidney injury on admission, secondary to poor oral intake and new onset dysphagia. After being transferred to an endocrine ward, upon noting the presence of a goitre, routine thyroid function tests were performed which revealed profound thyrotoxicosis (Free T4 of 83.1 pmol/L and TSH <0.01 mU/L). Ultrasound scanning of the neck revealed gross bilateral thyroid lobe and thymic enlargement, with a non-homogenous echo pattern and several hypoechoic and isoechoic nodules with no increased vascularity, appearances consistent with a hyperplastic multi-nodular goitre.
A detailed speech therapy assessment revealed severe oral stage dysphagia and enteral feeding via a Nasogastric tube was advised. Ms SM promptly commenced a tailored feeding regimen and anti thyroid medication (carbimazole 30 mg once daily).
An EMG performed 3 weeks after admission showed normal sensory and motor conduction in the distal upper and lower limbs, however, as suspected, also showed pronounced myopathic changes in the muscle tested (the right bicep). Ms SMs thyroid function was monitored closely, and required an increase of the carbimazole dosing to 60 mg once daily. She continued to receive supportive management, with input from the nutrition and physiotherapy teams and managed to regain her normal level of physical function 5 weeks into her admission.
This case visibly demonstrates the profound effect severe uncontrolled hyperthyroidism may have on an individuals physical status, and overall health, as well as specifically showing the rarely seen myopathic changes that occur at the level of the muscle.