Hyper and hypo-parathyroidism both lead to psychiatric disorder. In the former the hypercal-caemia is responsible for an acute or chronic organic reaction, depending on the speed with which the calcium has risen. The hypocalcaemia of the latter is more likely to present as tetany, and enters into the differential diagnosis of hysterical over-breathing (Hill et al, 1987). Hypo-parathyroidism most commonly follows inadvertent parathyroidectomy during thyroiddectomy when an abrupt fall in serum calcium can precipitate psychiatric disturbance. The mental state is closely related to the serum calcium level. If this is borderline there may only be symptoms such as anxiety, depression and tension, but with lower levels acute confusion may result. More chronic symptoms occur in long standing hypo-parathyroidism, such as poor concentration, emotional lability and impaired intelligence (Kendall & Zealley, 1983).