Context: Normocalcaemic hypoparathyroidism (NHYPO) is characterized by low levels of parathyroid hormone (PTH) with normal levels of calcium. There is little in the current literature on this disease, with only two studies published on its prevalence, while its natural history remains relatively unknown.
Objectives: To identify the prevalence of NHYPO in a UK referral population and to study the natural history of the disorder.
Design: Retrospective study. Five-year follow-up.
Patients: 6280 patients referred for a BMD measurement in a Metabolic Bone referral centre.
Measurements: Prevalence of NHYPO and variability of calcium.
Results: Based on laboratory results on the index day, 22 patients with NHYPO were identified. Four patients were excluded due to non-PTH-induced hypocalcaemia and unconfirmed data. The final prevalence was 0.29%. Only 67% had persistent normocalcaemia, and the rest had intermittent hypocalcaemia. Two of these patients also had persistently low PTH on two occasions. Most of the patients had one PTH measurement available. No patient developed permanent hypoparathyroidism.
Conclusions: The prevalence calculated from this UK referral population is lower when compared to results from previous studies. NHYPO patients often have episodes of hypocalcaemia with some cases having no apparent reason for calcium levels below the reference range.
Keywords: calcium; calcium metabolism disorders; epidemiology; hypocalcaemia; hypoparathyroidism; parathyroid diseases; parathyroid gland; prevalence.
© 2020 The Authors. Clinical Endocrinology published by John Wiley & Sons Ltd.