Epidemiology and health related quality of life in hypoparathyroidism in Norway.

OBJECTIVE: The epidemiology of hypoparathyroidism (HP) is largely unknown. We aimed to determine prevalence, etiologies, health related quality of life (HRQoL) and treatment pattern of HP. METHODS: Patients with HP and 22q11 deletion syndrome (DiGeorge syndrome) were identified in electronic hospital registries. All identified patients were invited to participate in a survey. Among patients who responded, HRQoL was determined by Short Form 36 (SF-36) and Hospital Anxiety and Depression scale (HADS). Autoantibodies were measured and candidate genes (CaSR, AIRE, GATA3 and 22q11-deletion) were sequenced for classification of etiology. RESULTS: We identified 522 patients (511 alive) and estimated overall prevalence at 102 per million divided among post-surgical HP (64 per million), non-surgical HP (30 per million) and pseudo-HP (8 per million). Non-surgical HP comprised autosomal dominant hypocalcemia (21%), autoimmune polyendocrine syndrome type 1 (17%), DiGeorge/22q11 deletion syndrome (15%), idiopathic HP (44%), and others, 4%. Among the 283 respondents (median age 53 years (range 9-89), 75% females), seven formerly classified as idiopathic were reclassified after genetic and immunological analyses, whereas 26 (17% of non-surgical HP) remained idiopathic. Most were treated with vitamin D (94%) and calcium (70%), and 10 received parathyroid hormone. HP patients scored significantly worse than the normative population on SF-36 and HADS; patients with post-surgical scored worse than those with non-surgical HP and pseudo-HP, especially on physical health. CONCLUSIONS: We found higher prevalence of non-surgical HP in Norway than reported elsewhere. Genetic testing and autoimmunity screening of idiopathic HP identified a specific cause in 21%. Further research is necessary to unravel the causes of idiopathic HP and to improve the reduced HRQoL reported by HP patients.