Lind L, Wengle B, Sørensen O H, Wide L, Akerström G, Ljunghall S
Department of Internal Medicine, Gävle Hospital, Sweden.
Acta Endocrinol (Copenh). 1989 Feb;120(2):250-6. doi: 10.1530/acta.0.1200250.
The parathyroid gland possesses receptors for 1,25-dihydroxyvitamin D3, the active metabolite of the vitamin D system, and in vitro experiments have shown that 1,25-dihydroxyvitamin D3 can inhibit the secretion of PTH. In this study 31 subjects who had displayed persistent mild hypercalcemia for 14 years and presumably had mild primary hyperparathyroidism (HPT) were challenged with 1.0 microgram alphacalcidol (1 alpha-(OH)-vitamin D3) over 6 months in a double-blind, placebo-controlled study. Before initiation of therapy, the hyperparathyroid subjects showed lower serum levels of 1,25-dihydroxyvitamin D in relation to PTH or calcium when compared with age- and sex-matched controls. Treatment induced a slight rise in serum calcium (0.05 mmol/l), but no significant decrease of the PTH levels. Eighteen of the subjects thereafter entered an open study with a higher dose of alphacalcidol (2.0 micrograms) over 1 year. Although this high dose induced a marked rise in serum calcium (0.17 mmol/l), there was only a transient reduction of the PTH levels. Thus, during long-term condition there was an escape from the suppressive action of the elevated calcium concentrations and no evidence of a specific inhibition of PTH secretion by a small oral dose of active vitamin D.
甲状旁腺拥有维生素D系统的活性代谢产物1,25 - 二羟维生素D3的受体，体外实验表明1,25 - 二羟维生素D3可抑制甲状旁腺激素（PTH）的分泌。在本研究中，31名持续轻度高钙血症达14年且推测患有轻度原发性甲状旁腺功能亢进（HPT）的受试者，在一项双盲、安慰剂对照研究中接受了为期6个月的1.0微克阿法骨化醇（1α - (OH)-维生素D3）治疗。在开始治疗前，与年龄和性别匹配的对照组相比，甲状旁腺功能亢进的受试者血清中1,25 - 二羟维生素D与PTH或钙的水平较低。治疗使血清钙略有升高（0.05 mmol/L），但PTH水平无显著下降。此后，其中18名受试者进入一项开放研究，接受为期1年的更高剂量阿法骨化醇（2.0微克）治疗。尽管高剂量使血清钙显著升高（0.17 mmol/L），但PTH水平仅短暂降低。因此，在长期情况下，机体对升高的钙浓度的抑制作用产生了逃逸，且未发现小剂量口服活性维生素D对PTH分泌有特异性抑制作用的证据。
