This is a brief history of hypothyroidism and the contribution of Sir William Withey Gull. Hypothyroidism and its complications provide many clinical puzzles for neurologists.

The thyroid had no known function until the end of the 19th century. In the wake of the term coined by Claude Bernard (1813–1878) in 1855, "internal secretion", and his concept of the milieu interieur, Sir William Withey Gull in 1873 was one of the first to understand that the cause of myxoedema is atrophy of the thyroid gland.

Gull’s seminal paper¹ related the changed …