Prevalence of clinical remission in patients with sporadic idiopathic hypoparathyroidism

Abstract

Background: Remission of disease activity is a characteristic feature of autoimmune endocrine disorders such as Graves' disease, Addison's disease and occasionally in patients with premature ovarian failure. Autoimmunity is also implicated in sporadic idiopathic hypoparathyroidism (SIH) with clinical remission of disease reported in three cases. Objective: To assess the rate of remission in patients with sporadic idiopathic hypoparathyroidism and review the cases reported so far. Subjects and methods: Subjects included 53 patients (M:F, 24:29) with SIH who had been symptomatic for at least 1 year (range 1-31 years). They were treated with calcium and 1-α -(OH)D₃/cholecalciferol therapy and had a mean duration of follow up of 5.0 ± 3.2 years. Treatment was withdrawn in two stages in the patients who maintained normal levels of serum total calcium during the preceding year of treatment. In stage-1, the dose of therapy was reduced to half and subsequently all treatment was stopped (stage 2) in those patients who maintained normal serum total calcium levels on the reduced dose. Remission of SIH was defined as maintenance of normal serum total (≥ 2.12 mmol/l) and ionized calcium, inorganic phosphorus and serum intact parathyroid hormone (iPTH) for at least 3 months after withdrawal of calcium and 1-α -(OH)D₃/cholecalciferol therapy. Calcium sensing receptor autoantibodies (CaSRAb) were determined by Western blot. Results: Two of the 53 patients (3.8%) with SIH stayed in remission for 1 year after complete withdrawal of therapy. CaSRAb was absent in both the cases. The clinical features, age at onset and duration of hypocalcaemic symptoms in cases with remission were comparable to those who did no show remission. Conclusion: Sporadic idiopathic hypoparathyroidism is not irreversible as is widely believed and spontaneous remission of disease may occur in 3.8% of patients.