In the first of a short series of articles on endocrinology, H S Randeva and P M G Bouloux explain the various manifestations of thyrotoxicosis and tell you how to diagnose and treat it
Thyrotoxicosis or hyperthyroidism is the clinical syndrome caused by an excess of circulating free thyroxine and free triiodothyronine, or both. It is common, affecting about 2% of women and 0.2% of men.
Of the causes of thyrotoxicosis (box 1), Graves' disease is the most common (70-80%); toxic thyroid adenoma, toxic multinodular goitre, and subacute thyroiditis account for most of the remainder. Surreptitious overdosing (factitious thyrotoxicosis) is occasionally seen.