Apathetic hyperthyroidism in middle age.

Apathetic hyperthyroidism was first described in the medical literature by Lahey in 1931. It is a form of hyperthyroidism found principally in the elderly population. In this disorder the usual hyperkinetic presentation of thyrotoxicosis is replaced by apathy and inactivity, often leading to an erroneous psychiatric diagnosis. Although there is a paucity of literature on apathetic hyperthyroidism, it has been described in the elderly and as an extremely rare complication of hyperthyroid disorder in children. It was described only rarely in middle age. The following case highlights the diagnostic and therapeutic dilemmas encountered in a middle-aged patient who presented with dementia and apathetic hyperthyroidism.