Borghi L, Meschi T, Guerra A, Bergamaschi E, Mutti A, Novarini A
Institute of Semeiotica Medica, University of Parma Medical School, Italy.
Clin Chim Acta. 1995 Jul 31;239(1):1-11. doi: 10.1016/0009-8981(95)06092-r.
Urinary macromolecules have attracted great interest because of their possible role as both promoters and inhibitors of calcium oxalate (CaOx) crystallization and it remains unclear whether there is any difference, in their nucleating activity, between stone formers and controls. We selected 9 male idiopathic CaOx stone formers whose 24-h urines presented no evidence of common urinary stone risk factors such as hypercalciuria, hyperoxaluria, hyperuricosuria, hypocitraturia, hypomagnesiuria or low glycosaminoglycans excretion and 12 male controls (matched for age and body weight) whose 24-h urines did not differ from those of stone formers. The study of urinary CaOx nucleation was made in freshly voided overnight urines whose biochemical composition was almost identical in the two groups. In filtered (0.22 micron) and ultrafiltered (10 kDa) urine we performed an oxalate tolerance test to determine the permissible increment of oxalate, the oxalate level for nucleation and the permissible increment of CaOx relative supersaturation (CaOx RS). In filtered urine from stone formers the permissible increment of oxalate was lower than controls (30 +/- 10.2 vs. 46.7 +/- 9.7 mg/l, P = 0.001), the oxalate level for nucleation was lower (64.4 +/- 14.2 vs. 79.5 +/- 15.6 mg/l, P = 0.035) and the permissible increment of CaOx RS was also lower (9.71 +/- 2.59 vs. 13.39 +/- 3.62, P = 0.018). In ultrafiltered urine these differences disappeared because the removal of macromolecules in stone formers significantly enhanced the oxalate-tolerance values. The difference between the change of the oxalate permissible increment of filtered and ultrafiltered urine allowed a distinction to be made between stone formers and controls that was not feasible in other ways (7.6 +/- 5.3 vs. 3.3 +/- 5.9 mg/l, P < 0.0001). The study suggests that, in idiopathic CaOx stone formers free from common urinary risk factors of CaOx crystallization, there is an increased tendency for CaOx nucleation in urine, which is mediated by macromolecular components.
尿大分子因其在草酸钙（CaOx）结晶过程中可能同时起到促进和抑制作用而备受关注，目前尚不清楚结石形成者与对照组在其成核活性方面是否存在差异。我们选取了9名男性特发性CaOx结石形成者，他们24小时尿液中未出现高钙尿症、高草酸尿症、高尿酸尿症、低枸橼酸尿症、低镁尿症或低糖胺聚糖排泄等常见尿路结石风险因素的证据；还选取了12名男性对照组（年龄和体重匹配），他们的24小时尿液与结石形成者的尿液无差异。对两组生化组成几乎相同的晨尿进行了尿CaOx成核研究。在过滤（0.22微米）和超滤（10 kDa）尿液中，我们进行了草酸耐受性试验，以确定草酸的允许增量、成核的草酸水平以及CaOx相对过饱和度（CaOx RS）的允许增量。结石形成者过滤尿液中草酸的允许增量低于对照组（30±10.2对46.7±9.7毫克/升，P = 0.001），成核的草酸水平较低（64.4±14.2对79.5±15.6毫克/升，P = 0.035），CaOx RS的允许增量也较低（9.71±2.59对13.39±3.62，P = 0.018）。在超滤尿液中，这些差异消失了，因为结石形成者中大分子的去除显著提高了草酸耐受性值。过滤尿液和超滤尿液中草酸允许增量变化的差异使得能够区分结石形成者和对照组，而这用其他方法是不可行的（7.6±5.3对3.3±5.9毫克/升，P < 0.0001）。该研究表明，在没有CaOx结晶常见尿路风险因素的特发性CaOx结石形成者中，尿液中CaOx成核的倾向增加，这是由大分子成分介导的。
