Current therapy of hypoparathyroidism--a survey of German endocrinology centers

Hypoparathyroidism is a rare disease with hypocalcemia as the leading symptom. In adults, hypocalcemia is mainly due to postoperative hypoparathyroidism. Hypoparathyroidism requires lifelong therapy with vitamin D or metabolites. Genuine vitamin D3 (Vigantol) is the most economic treatment of hypoparathyroidism; however, vitamin D3 has a very long biologic half life with the subsequent danger of chronic vitamin D intoxication. Dihydrotachysterol (A.T.10), an analogue of vitamin D, acts similarly and can be used alternatively. 1,25-dihydroxyvitamin D3 (Rocaltrol), the biologically active metabolite of vitamin D3, is very potent, but bears the danger of causing acute intoxication; it has a short half life and is more expensive than vitamin D3. A further metabolite, 1-hydroxy-vitamin D3 (alfacalcidol, Doss, EinsAlpha) is available for therapeutic use. Clinical intervention trials concerning the best therapy and management of hypoparathyroidism are lacking. We therefore surveyed German physicians treating hypoparathyroidism. Furthermore, we carried out a retrospective study of 45 patients treated in our endocrinology department during the last 8 years and examined whether measurement of 25(OH)-vitamin D3 is helpful in managing hypoparathyroidism. The data from 59 children and 270 adults could be completed in the survey. 1,25-dihydroxyvitamin D3 was the only vitamin D agent that was administered in the treatment of children, whereas in adults 52% were treated with dihydrotachysterol, 28% with genuine vitamin D3, and 20% with 1,25-dihydroxyvitamin D3. There was a positive correlation between serum 25(OH)-vitamin D3 levels and administered vitamin D3 doses. In patients treated with vitamin D3, serum calcium levels correlated significantly with serum 25(OH)-vitamin D3 levels whereas they did not correlate with administered calcium doses. Thus: (1) in Germany dihydrotachysterol is preferred for therapy of hypoparathyroidism in adults and (2) measurement of serum 25(OH)-vitamin D3 may be helpful in assessing efficacy of therapy and compliance in patients treated with vitamin D3.