Mazzaferro S, Chicca S, Pasquali M, Zaraca F, Ballanti P, Taggi F, Coen G, Cinotti G A, Carboni M
Department of Clinical Science, University 'La Sapienza', Rome, Italy.
Nephrol Dial Transplant. 2000 Jun;15(6):877-82. doi: 10.1093/ndt/15.6.877.
Available data on changes in serum levels of bone markers after parathyroidectomy (PTx) in dialysis patients are not uniform. Changes are thought to be due to either a reduction in PTH activity per se or to a direct effect of vitamin D therapy on bone cells. We aimed to verify whether treatment with vitamin D modifies serum levels of markers of bone synthesis (alkaline phosphatase (AP), osteocalcin (BGP), procollagen type I C-terminal peptide (PICP)) and resorption (collagen type I C-terminal peptide (ICTP)) within a period of 15 days in haemodialysis patients with severe secondary hyperparathyroidism following PTx.
We randomized two groups (A, treatment and B, placebo, 10 patients each) with comparable basal PTH values and measured bone markers 3, 7 and 15 days after surgery. All patients were treated with calcium supplements (i.v. and p.o.), and group A also received calcitriol (2.4+/-1.0 microg/day, p.o.).
In both groups, PTx induced significant changes in all the markers evaluated, except for BGP in group B. Compared to basal values, ICTP decreased from 481+/-152 ng/ml in group A and 277+/-126 ng/ml in group B to 267+/-94 and 185+/-71 ng/ml (M+/-SD) respectively, and PICP increased from 307+/-139 ng/ml in group A and 309+/-200 ng/ml in group B to 1129+/-725 and 1231+/-1267 ng/ml (M+/-SD) respectively, within 3 days of surgery. AP values increased after 15 days from 1115+/-734 mU/ml in group A and 1419+/-1225 mU/ml in group B to 1917+/-1225 and 1867+/-1295 mU/ml (M+/-SD) respectively. On the contrary, mean values of BGP were never different from basal levels after PTx in either group. In the two groups, the pattern of changes of all the bone markers after PTx was almost identical. Group A patients predictably required lower doses of oral calcium supplements to correct hypocalcaemia (16. 9+/-5.7 vs 22.1+/-5.0 g/10 days; M+/-SD, P<0.04).
The opposite behaviour of serum PICP and ICTP after PTx, in both the treated and untreated groups suggests that quantitative uncoupling between bone synthesis and resorption is responsible for hypocalcaemia. This phenomenon, as reflected by the evaluated bone markers, is unaffected by calcitriol. Based on our data we conclude that immediately after parathyroid surgery, vitamin D therapy does not influence bone cell activity, but improves hypocalcaemia mainly through its known effect on intestinal calcium absorption.
关于透析患者甲状旁腺切除术后（PTx）血清骨标志物水平变化的现有数据并不一致。这些变化被认为要么是由于甲状旁腺激素（PTH）活性本身降低，要么是维生素D治疗对骨细胞的直接作用。我们旨在验证在PTx后患有严重继发性甲状旁腺功能亢进的血液透析患者中，维生素D治疗是否会在15天内改变骨合成标志物（碱性磷酸酶（AP）、骨钙素（BGP）、I型前胶原C端肽（PICP））和骨吸收标志物（I型胶原C端肽（ICTP））的血清水平。
我们将两组（A组为治疗组，B组为安慰剂组，每组10例患者）具有可比基础PTH值的患者随机分组，并在术后3天、7天和15天测量骨标志物。所有患者均接受钙补充剂治疗（静脉内和口服），A组还接受骨化三醇治疗（2.4±1.0μg/天，口服）。
在两组中，PTx均引起了除B组中的BGP外所有评估标志物的显著变化。与基础值相比，ICTP在A组中从481±152ng/ml降至267±94ng/ml，在B组中从277±126ng/ml降至185±71ng/ml（均值±标准差），PICP在A组中从307±139ng/ml升至1129±725ng/ml，在B组中从309±200ng/ml升至1231±1267ng/ml（均值±标准差），均在术后3天内。AP值在15天后从A组的1115±734mU/ml和B组的1419±1225mU/ml分别升至1917±1225mU/ml和1867±1295mU/ml（均值±标准差）。相反，两组中PTx后BGP的均值与基础水平相比从未有差异。在两组中，PTx后所有骨标志物的变化模式几乎相同。A组患者可预见地需要较低剂量的口服钙补充剂来纠正低钙血症（16.9±5.7 vs 22.1±5.0g/10天；均值±标准差，P<0.0）。
在治疗组和未治疗组中，PTx后血清PICP和ICTP的相反变化表明骨合成与骨吸收之间的定量解偶联是低钙血症的原因。如所评估的骨标志物所反映的这种现象不受骨化三醇的影响。基于我们的数据，我们得出结论，甲状旁腺手术后立即给予维生素D治疗不会影响骨细胞活性，但主要通过其对肠道钙吸收的已知作用来改善低钙血症。
