Aim: We aimed to undertake a population-based approach to describing the prevalence and incidence of chronic hypoparathyroidism. There are very few reports on the epidemiology of this condition.
Methods: Data linkage of all biochemistry, hospital admissions, prescribing and death records was undertaken in Tayside Scotland (population 400,000) from 1988 to 2015. Patients with at least 3 serum calcium concentrations below the reference range from an out-patient setting and who fulfilled at least one of these criteria; had either previous neck surgery/irradiation, a low serum PTH or treatment with Vitamin D were included in the study. Patients with prior severe chronic kidney disease were excluded. Patients were subcategorised into either those with a surgical or a non-surgical cause, and patients with secondary hypoparathyroidism e.g. hypomagnesaemia, were identified.
Results: Overall 18,955 patients with hypocalcaemia were identified of whom 222 patients were identified with primary hypoparathyroidism, 116 with post-surgical and 106 with non-surgical hypoparathyroidism. The prevalence of primary hypoparathyroidism was 40 per 100,000 of the population in 2015. Post surgical and non-surgical rates were 23 and 17 per 100,000 respectively, with 80% of the former and 64% of the latter being female. The annual incidence varied from 14 100,000 with a mean serum calcium at diagnosis being 1.82 mmol/l (SD±0.24). Activated Vitamin D was used in 48% of post-surgical cases and 43% of non-surgical cases with 71% all patients being prescribed calcium and/or standard Vitamin D. Over 90% of post-surgical and 64% of nonsurgical cases were prescribed thyroxine and/or hydrocortisone.
Conclusions: Using a population-based approach we identified a large number of patients with non-surgical hypoparathyroidism, many with mild hypocalcaemia not requiring treatment. Two thirds of these patients were on hydrocortisone and/or thyroxine suggesting an autoimmune aetiology.