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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-alpha-(OH)D(3)/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 Treatment was withdrawn in two stages in the patients who maintained normal levels of serum total calcium during the preceding year of treatment.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 (>or=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-alpha-(OH)D(3)/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.

Objective: Because vitamin D synthesis is lower in a heavily pigmented skin than in a lighter skin, the relative contribution of determinants to the vitamin D concentration might differ between ethnic groups. The aim of this study was to assess the prevalence of vitamin D deficiency and the relative contribution of vitamin D consumption and exposure to sunlight to the vitamin D concentration in a multiethnic population., Design: Cross-sectional study., Patients: A total of 613 adults aged 18-65 years from a random sample from general practices in the Netherlands (52 degrees N, 2003-05), stratified according to gender and ethnic group., Measurements: Serum 25-hydroxyvitamin D [25(OH)D], PTH, ethnic group, sunlight exposure, consumption of foods and supplements rich in vitamin D., Results: The prevalence (95% confidence interval) of vitamin D deficiency [serum 25(OH)D < 25 nmol/l] was higher in Turkish (41.3%; 32.5-50.1), Moroccan (36.5%; 26.9-46.1), Surinam South Asian (51.4%; 41.9-60.9), Surinam Creole (45.3%; 34.0-56.6), sub-Saharan African (19.3%; 9.1-29.5) and other adults (29.1%; 17.1-41.1) compared to the indigenous Dutch (5.9%; 1.3-10.5). Modifiable, significant determinants (standardized regression coefficients) for serum 25(OH)D concentration were: consumption of fatty fish (0.160), use of vitamin D supplements (0.142), area of uncovered skin (highest category 0.136; middle category 0.028), use of tanning bed (0.103), consumption of margarine (0.093) and preference for sun (0.089). We found no significant modification of ethnic group on the effect of sunlight determinants., Conclusion: Of the modifiable determinants, fatty fish and supplements are the greatest contributors to the serum 25(OH)D concentration in a multiethnic population.

A comparison has been made between themetabolic consequences of daily administration for 6 weeks of 1.0 micrograms and 0.5 micrograms 1 alpha hydroxyvitamine D3 (1 alpha(OH)D3) in twenty patients with senile osteoporosis. There was no significant difference in the increase of calcium absorption which occurred in the two treatment groups between the beginning and end of the trial period. Serum and urinary calcium rose significantly in those receiving 1.0 micrograms 1 alpha(OH)D3 but not in the lower dosage group. Serum parathyroid hormone levels were suppressed in the higher dosage group only. There was a significantly greater rise of serum inorganic phosphate, and fall of serum magnesium, on the higher dosage, but no significant change in serum creatinine occurred in either group. It is, therefore, suggested that in long term therapy regimes for osteoporosis incorporating 1 alpha(OH)D3, 0.5 micrograms may be a more suitable daily dose than 1.0 micrograms 1 alpha(OH)D3.

Twenty-three patients with bone disease and chronic renal failure were treated for periods of 4--28 months with 1alpha-hydroxyvitamin D3 (1alpha-OHD3). Improvements in bone histology were consistently seen in patients with features both of osteitis fibrosa and osteomalacia but were not invariably observed in patients with osteitis fibrosa or osteomalacia alone (37 and 50% improved respectively). Several factors influencing the outcome of treatment were assessed on the basis of histological responses in bone. A low level of plasma calcium before treatment, rather than the dose of 1alpha-OHD3 tolerated, was the major detectable factor which favourably affected the histological outcome. Other factors examined, including initial plasma concentrations of phosphate, immunoreactive parathyroid hormone and alkaline phosphatase, and treatment with haemodialysis or dietary supplements of calcium did not apparently influence the response.

Assessment of 18 azotaemic patients treated with long-term 1alpha-hydroxyvitamin D3 (1alpha-OHD3) confirms the generally favourable effect of this analogue of 1,25-dihydroxyvitamin D3 in azotaemic osteodystrophy. Growing children with radiological rickets respond very well as do adults showing mild hyperparathyroidism with or without osteomalacia. However, patients with severe 'pure' hyperparathyroidism and features of autonomy do not respond well and in such patients 1alpha-OHD3 alone should be avoided. Phosphate restriction and occasionally a sub-total parathyroidectomy may be indicated in these patients.

This investigation confirms that 1alpha-hydroxyvitamin D3 (1alpha-OHD3) is a potent drug for the treatment of patients with pseudo-deficiency rickets (Balsan et al., 1975a; Reade et al., 1975; Prader et al., 1976). 1alpha-OHD3 corrects their intestinal malabsorption of calcium and phosphorus, normalizes their serum calcium and phosphate concentrations and promotes healing of skeletal lesions. This study also shows differences in the needs for 1alpha-OHD3 of children with PDR. Three factors appear to be of importance: familial sensitivity, severity of chronic secondary hyperparathyroidism, and periods of increased growth velocity. Tolerance to long-term 1alpha-OHD3 therapy, at doses varying from 0.5 to 2 microgram/d is excellent. Surveillance of patients should include regular measurements of 24 h urinary excretion of calcium, since hypercalciuria is the first signal of overdosage.

Results of 1alpha-hydroxyvitamin D3 therapy in twelve children with renal bone disease are described. Nine of the twelve children showed a good response to 0.05--0.08 microgram/kg/day. Hypercalcaemia was the only side effect and proved easy to manage because of the short half-life of 1alpha-OHD3.