ABSTRACT
Elevated body temperature [fever] has long been observed as a feature of many endocrine disorders such as thyroiditis, thyrotoxic storm, adrenocortical insufficiency and, less commonly, phaeochromocytoma. However, fever as a sole presenting symptom of thyrotoxicosis is extremely rare. Two male patients are described who presented with fever of unknown origin, with the initial suspicion of infection. The thyroid gland was minimally enlarged with no other signs or symptoms of thyrotoxicosis. In both cases the conclusion that thyrotoxicosis was the cause of the fever was made after all tests for other common and unusual causes of fever were negative or normal, while thyroid function tests, thyroid scan and uptake were abnormal. Fever subsided following propranolol and radioactive iodine therapy. Though fever is a rare presenting symptom of thyrotoxicosis it should be considered in the differential diagnosis of fever of unknown origin