Hypocalcaemia with zonular cataract due to idiopathic hypoparathyroidism. With a note on the prevalence of severe hypocalcaemia in a health screening.

A 59-year-old woman with idiopathic hypoparathyroidism who had tetany and zonular cataract is described. Twelve years ago she had had a period with cramps and convulsions, followed by an absence of symptoms for several years. Judging from the distance between the opacity of cataract and the surface of the lens, the onset of the cataract was estimated to have occurred 11 years ago and the apparent cessation of cataract development 10 years ago. It is suggested that the absence of hypocalcaemic symptoms during the last 10 years was associated with an increase in serum calcium levels, possibly connected with the onset of menopause. The occurrence of hypocalcaemia was analyzed in a health-screened population of 15 903 persons. Nine of the subjects were found to have a serum calcium level of less than 2.10 mmol/l, giving a prevalence of 0.6%0. None had primary hypoparathyroidism, which illustrates the rarity of this condition.