Division of Clinical Nephrology and Rheumatology, Niigata University Graduate School of Medical and Dental Sciences, Faculty of Medicine, Niigata University, Chuoku, Niigata City, Japan.
Scand J Rheumatol. 2010;39(1):33-7. doi: 10.3109/03009740903042402.
Chronic kidney disease is a predictor of end-stage renal disease, and evaluating the glomerular filtration rate (GFR) is necessary to make a definite diagnosis. We assessed the utility of serum cystatin C (cysC) for identifying a reduced GFR in patients who have rheumatoid arthritis (RA) with secondary amyloidosis.
Fifty patients with RA and secondary amyloidosis (mean age 60.9+/-11.2 years; 45 women) were evaluated. The revised 24-h creatinine clearance (r24-hC(Cr)), which was determined by multiplying the original value by 0.719, was used as a reference for the GFR. The screening potential of the serum cysC and some estimates of the GFR calculated from the serum cysC (cysC-eGFR: eGFR(Hoek) and eGFR(Rule)) for detecting a reduced GFR (r24-hC(Cr)<60 mL/min/1.73 m(2)) were analysed.
Both cysC-eGFRs were strongly correlated with the r24-hC(Cr) (eGFR(Hoek), r=0.846, p<0.001; eGFR(Rule), r=0.820, p<0.001). The difference between the average eGFR(Rule) (37.1+/-31.2 mL/min/1.73m(2)) and average r24-hC(Cr) (35.3+/-30.9 mL/min/1.73 m(2)) was small, whereas eGFR(Hoek) and sCr-eGFR were higher than eGFR(Rule) and r24-hC(Cr). In receiver operating characteristic (ROC) curve analyses of a reduced GFR, serum cysC gave a greater area under the curve (AUC=0.958) than the sCr-eGFR (0.939-0.942). The specificity and positive predictive value (PPV) reached 100% when serum cysC >1.365 mg/L was used.
Serum cysC can identify a reduced GFR more accurately than sCr-eGFRs. Serum cysC >1.09 mg/L (i.e. eGFR(Rule)<60 mL/min/1.73 m(2)) could be a marker of a reduced GFR, and serum cysC >1.365 mg/L would strongly suggest a reduced GFR in patients who have RA with secondary amyloidosis.
慢性肾病是终末期肾病的预测因素，评估肾小球滤过率（GFR）对于明确诊断是必要的。我们评估了血清胱抑素 C（cysC）在患有类风湿关节炎（RA）合并继发性淀粉样变性的患者中识别肾小球滤过率降低的作用。
评估了 50 例 RA 合并继发性淀粉样变性患者（平均年龄 60.9+/-11.2 岁；45 名女性）。使用血清胱抑素 C 计算的肾小球滤过率（cysC-eGFR：eGFR（Hoek）和 eGFR（Rule））乘以 0.719 后的修正 24 小时肌酐清除率（r24-hC（Cr））作为 GFR 的参考值。分析了血清 cysC 以及从血清 cysC 计算的一些 GFR 估计值（cysC-eGFR：eGFR（Hoek）和 eGFR（Rule））用于检测肾小球滤过率降低（r24-hC（Cr）<60 mL/min/1.73 m（2））的筛查能力。
cysC-eGFR 与 r24-hC（Cr）均呈强相关（eGFR（Hoek），r=0.846，p<0.001；eGFR（Rule），r=0.820，p<0.001）。平均 eGFR（Rule）（37.1+/-31.2 mL/min/1.73 m（2））与平均 r24-hC（Cr）（35.3+/-30.9 mL/min/1.73 m（2））之间的差值较小，而 eGFR（Hoek）和 sCr-eGFR 则高于 eGFR（Rule）和 r24-hC（Cr）。在肾小球滤过率降低的受试者工作特征（ROC）曲线分析中，血清 cysC 的曲线下面积（AUC）大于 sCr-eGFR（0.939-0.942）（AUC=0.958）。当血清 cysC >1.365 mg/L 时，特异性和阳性预测值（PPV）达到 100%。
血清 cysC 比 sCr-eGFR 更能准确地识别肾小球滤过率降低。血清 cysC >1.09 mg/L（即 eGFR（Rule）<60 mL/min/1.73 m（2））可能是肾小球滤过率降低的标志物，而血清 cysC >1.365 mg/L 则强烈提示 RA 合并继发性淀粉样变性患者的肾小球滤过率降低。
