Fatal thyrotoxic periodic paralysis with normokalemia

We present a 10-year-old girl who presented to our emergency services with difficulty in breathing of 2-days duration and progressive weakness of a month's duration. In a previous admission elsewhere, she had not been detected to have hyperthyroidism or electrolyte abnormalities. On admission, the child was in hypercapnic respiratory failure with tachycardia and hepatomegaly. A small goiter as well as signs of thyrotoxicosis were present. Laboratory investigations showed anemia, mildly elevated liver enzymes and serum potassium of 4.8mEq/L. Despite intubation and ventilation and other supportive management including propranolol, the patient could not be saved. Post-mortem biopsy of the thyroid showed diffuse hyperplasia of the follicles and muscles showed evidence of thyroid myopathy.