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High prevalence of nonsurgical hypoparathyroidism exists in Norway
Genetic, autoimmune and idiopathic hypoparathyroidism rates in Norway are higher than observed elsewhere, with many of the patients reporting a reduced health-related quality of life, according to recent study findings.
Marianne C. Astor, MD, a PhD student and consultant in endocrinology at the University of Bergen and Haukeland University Hospital, Bergen, Norway, and colleagues analyzed electronic medical records from 522 patients with hypoparathyroidism and 22q11.2 deletion syndrome (DiGeorge syndrome) identified between October 2010 and September 2013 (mean age, 51 years; 73% women). Within the cohort, 283 participants (mean age, 53 years; 75% women) completed a questionnaire that included time of diagnosis and symptoms, treatment and cause of disease (if known), the Short Form 36 (SF-36) and Hospital Anxiety and Depression scale (HADS). Also, blood and urine samples were collected. Researchers analyzed serum for total calcium, albumin, phosphate, magnesium, creatinine, thyroid-stimulating hormone and free thyroxine. Candidate genes (CaSR, AIRE, GATA3 and 22q11-deletion) were sequenced for classification of etiology.
Marianne C. Astor
Researchers estimated overall hypoparathyroidism prevalence to be 102 per million, with 64 per million estimated to be postsurgical hypoparathyroidism; 30 per million estimated to be nonsurgical and 8 per million estimated to be pseudohypoparathyroidism.
Among the 151 nonsurgical patients, 44% had idiopathic disease; 85 patients had genetic or autoimmune hypoparathyroidism, including 21% with autosomal dominant hypocalcemia, 17% with autoimmune polyendocrine syndrome type 1, 15% with DiGeorge syndrome and 4% with other types.
Among the 283 respondents, researchers reclassified seven patients with idiopathic disease after genetic and immunologic analyses; 26 participants (17% of nonsurgical hypoparathyroidism) remained idiopathic. The majority of the cohort was treated with active vitamin D formulations (94%) or calcium supplementation (90%); 10 received parathyroid hormone therapy.
“Despite testing for underlying causes, about one-third of nonsurgical patients remain idiopathic, which may conceal hitherto unidentified forms of [hypoparathyroidism],” the researchers wrote. “The medical history and clinical vigilance can to some extent guide the clinician to the underlying cause, but in many cases the cause is not obvious.”
Researchers found that patients with hypoparathyroidism had a lower quality of life in all dimensions of the SF-36 vs. healthy Norwegian population, whereas patients with pseudohypoparathyroidism had lower scores in three of eight dimensions. Patients with hypoparathyroidism had higher scores for anxiety, depression and total HADS vs. the healthy population.
“Further research into improved treatment options should include different PTH-delivering systems,” Astor told Endocrine Today. “Identification of the hitherto unknown causes of idiopathic hypoparathyroidism should provide a better understanding of the disease and holds promise for a more personalized approach in management.” – by Regina Schaffer
For more information:
Marianne C. Astor, MD, can be reached at the department of medicine at Haukeland University Hospital, Jonas Liesvei 65, 5021, Bergen, Norway; email: Marianne.catharina.astor@helse-bergen.no.
Disclosure: The researchers report no relevant financial disclosures.