Pitutaty insufficiency. Diagnosis masked by a toxic thyroid adenoma.

A patient with undiagnosed pituitary insufficiency who also had a toxic thyroid adenoma is presented. The T3 secreted by the adenoma apparently corrected the secondary thyroid failure, but also aggravated the secondary adrenal failure and almost precipitated adrenal crisis. The diagnostic work-up in such an unusual co-existence is discussed, in particular since the clinical diagnosis of pituitary insufficiency in the elderly is not easily established.