Ibrahim S, Mojiminiyi S, Barron J L
Department of Chemical Pathology and Metabolism, St Helier Hospital, Carshalton, Surrey, UK.
Nephrol Dial Transplant. 1995 Dec;10(12):2290-4. doi: 10.1093/ndt/10.12.2290.
The urine excretion of the pyridinium crosslinks of collagen, pyridinoline (PYD) and deoxypyridinoline (DPD) closely reflect bone resorption and their assay has been used as specific markers of mature collagen turnover. The aims of this study were to evaluate the use of these markers to predict the severity of osteodystrophy in patients with chronic renal failure.
Using an isocratic ion-paired reverse-phase high-performance liquid chromatography, PYD and DPD were determined in the serum, urine and dialysate of 48 patients with chronic renal failure undergoing haemodialysis (n = 28) or continuous ambulatory peritoneal dialysis (n = 20). Nineteen apparently healthy subjects were studied as controls.
In all groups, serum and urine crosslinks excretion showed poor correlation with age. In the patients urine PYD/creatinine and DPD/creatinine were significantly (P < or = 0.03 and < or = 0.001 respectively) higher than normal; urine PYD and DPD levels were highly correlated with each other (r = 0.98) and with serum PTH (r = 0.84 and 0.83 respectively). The mean (SD) predialysis serum PYD, 269 (334) nmol/l, was significantly (P < or = 0.003) elevated compared with normal patients, 4.1 (0.6) and pre-dialysis serum DPD was 82.9 (93.7) nmol/l. DPD was below the detection limit of the assay in normal sera. In the patients postdialysis decreases in serum PYD and DPD were statistically significant (P < 0.0002 and P < 0.0007 respectively). PYD and DPD were found in the dialysate of patients on haemodialysis as well as 24-h dialysate in patients on CAPD. Dialysate PYD and DPD were highly correlated with each other (r = 0.80) and with dialysate creatinine (r = 0.76 and r = 0.62 respectively). In the patients, the mean serum, urine and dialysate PYD and DPD increased with the duration on dialysis. These findings confirm that metabolic bone disease increases in patients with duration of chronic renal failure.
Estimation of serum crosslinks levels has potential as an additional tool in the diagnosis and monitoring of renal osteodystrophy. The ability to determine crosslink levels in serum and dialysate should be particularly useful in patients who are unable to produce urine.
胶原蛋白的吡啶交联物吡啶啉（PYD）和脱氧吡啶啉（DPD）的尿排泄量能密切反映骨吸收情况，其检测已被用作成熟胶原周转的特异性标志物。本研究的目的是评估这些标志物用于预测慢性肾衰竭患者骨营养不良严重程度的价值。
采用等度离子对反相高效液相色谱法，测定了48例接受血液透析（n = 28）或持续性非卧床腹膜透析（n = 20）的慢性肾衰竭患者的血清、尿液和透析液中的PYD和DPD。选取19名健康受试者作为对照进行研究。
在所有组中，血清和尿液交联物排泄量与年龄的相关性较差。患者组尿液中PYD/肌酐和DPD/肌酐显著高于正常水平（P分别≤0.03和≤0.001）；尿液中PYD和DPD水平彼此高度相关（r = 0.98），且与血清甲状旁腺激素（PTH）也高度相关（r分别为0.84和0.83）。透析前患者血清PYD的均值（标准差）为269（334）nmol/L，与正常患者的4.1（0.6）相比显著升高（P≤0.003），透析前血清DPD为82.9（93.7）nmol/L。正常血清中DPD低于检测限。患者透析后血清PYD和DPD的降低具有统计学意义（P分别<0.0002和P<0.0007）。在血液透析患者的透析液以及持续性非卧床腹膜透析患者的24小时透析液中均检测到PYD和DPD。透析液中PYD和DPD彼此高度相关（r = 0.80），且与透析液肌酐也高度相关（r分别为0.76和0.62）。在患者中，血清、尿液和透析液中PYD和DPD的均值随透析时间延长而增加。这些发现证实慢性肾衰竭患者的代谢性骨病会加重。
血清交联物水平的测定有潜力作为诊断和监测肾性骨营养不良的辅助工具。对于无尿患者，能够测定血清和透析液中的交联物水平可能会特别有用。
