Circulating 1,25-Dihydroxycholecalciferol After Intravenous Injections of l{alpha}-Hydroxycholecalciferol in Patients on Regular Haemodialysis

The formation of 1.25-dihydroxycholecalciferol (1.25-(OH)₂D₃after single intravenous injections of 1-hydroxycholecalciferol(1-OHD₃) was examined in four patients with chronic renal failureon regular haemodialysis. Following 1–3µg 1-OHD₃administered at weekly intervals, 1.25-(OH)₂D₃ appeared in thecirculation within 1 h, and peak concentrations were reachedbetween 2 h and 5 h. By 8 h serum 1.25-(OH)₂D₃ concentrationshad started declining and by 44 h they had returned to baselineafter 1µg 1-OHD₃ but they were still above basal after2 and 3 µg by an average of 30 pmol/l. One week afterinjections, concentrations were back to basal in all patientsstudied. The serum 1,25-(OH)₂D₃ dose response to injected la-OHDwas linear, indicating ample capacity of the liver 25-hydroxylaseto further hydroxylate 1-OHD. However, examination of the individualresponses revealed lower increments in serum 1.25-(OH)₃ concentrationsin the patients with the highest basal serum 25-hydroxyvitaminD concen trations. Intravenous 1-OHD₃ may be useful in the furtherstudy of the interactions between 1.25-(OH)₂₃ calcium and PTHin chronic renal failure, as well as of the hepatic metabolismof vitamin D.     

钙与阿法骨化醇对老年男性骨质疏松患者骨密度及骨代谢的影响

目的：探讨钙与阿法骨化醇治疗老年男性骨质疏松患者的疗效及安全性。方法：原发性骨质疏松男性患者80例，随机分成对照组和治疗组，每组40例。对照组每天口服钙剂1片(钙尔奇D，每片含元素钙600 mg，含维生素D 125 U)；治疗组每天在口服钙剂1片的同时，加服阿法骨化醇0.5 μg，连续治疗12个月。在治疗前、治疗后12个月分别测量腰椎(L2～4)及股骨颈骨密度(BMD)、骨代谢指标——骨钙素(BGP)、I型胶原C端异构肽(β CTX)、血钙、血磷、肝肾功能等。结果：治疗12个月后，治疗组在腰椎侧位BMD、股骨颈BMD较治疗前均明显增加(P＜0.01)，血清BGP增高明显(P＜0.01)，β CTX下降明显(P＜0.01)；对照组腰椎L2 4侧位BMD无明显变化(P＞0.05)，股骨颈BMD有明显下降(P＜0.01)，血清BGP无明显改变(P＞0.05)，β CTX增高显著(P＜0.05)。两组肝肾功能，血、尿常规治疗前后差异无显著性(P＞0.05)。结论：钙加阿法骨化醇可预防和治疗老年男性骨质疏松，疗效显著，而单纯补钙并不能安全预防骨量的丢失。