Schwartz G J, Furth S, Cole S R, Warady B, Muñoz A
Department of Pediatrics, University of Rochester School of Medicine, Golisano Children's Hospital at Strong, Rochester, New York 14642, USA.
Kidney Int. 2006 Jun;69(11):2070-7. doi: 10.1038/sj.ki.5000385.
To guide the design of a nation-wide cohort study of chronic kidney disease in children, we determined how iohexol plasma disappearance curves could be used in children to measure glomerular filtration rate (GFR). Iohexol (5 ml) was administered intravenously and blood samples were obtained at 10, 20, 30, 60, 120, 240, 300, and 360 min after injection (N=29) and assayed by high performance liquid chromatography. Four urines were also collected following the injection. Intra-assay coefficient of variation (CV) in serum was 1.3% at 100 mg/l, 2.6% at 15 mg/l, and 3.4% for duplicate unknowns. GFR(9) was computed from iohexol dose and area under the nine-point blood disappearance curve, using double exponential modeling. Only 2.8% of 254 data points deviated by >3 CV from the curves. GFR(4) calculated from 10, 30, 120, and 300 min points correlated well with GFR(9) (r=0.999) and showed no bias (means+/-s.d. of GFR(9) and GFR(4)=59.3+/-36.3 and 59.4+/-36.0 ml/min per 1.73 m(2)). Relationship of GFR(9) and one-compartment GFR followed quadratic equation as previously reported by Brochner-Mortensen, allowing GFR to be calculated from 120 and 300 min points. This GFR(2) correlated well with GFR(9) (r=0.986). Estimated GFR from Schwartz height/creatinine formula correlated with GFR(9)(r=0.934) but overestimated GFR by 12.2 ml/min per 1.73 m(2). Urine iohexol clearance was poorly correlated (r=0.770) with GFR(9) owing to variability in urine collections (median CV=24%). GFR can be measured accurately using four-point iohexol plasma disappearance (in most cases, two points suffice); estimated GFR and urinary clearances are less useful.
为指导一项全国性儿童慢性肾脏病队列研究的设计，我们确定了如何在儿童中利用碘海醇血浆消失曲线来测量肾小球滤过率（GFR）。静脉注射碘海醇（5毫升），并在注射后10、20、30、60、120、240、300和360分钟采集血样（N = 29），采用高效液相色谱法进行检测。注射后还收集了4份尿液。血清中批内变异系数（CV）在100毫克/升时为1.3%，在15毫克/升时为2.6%，重复未知样本为3.4%。利用双指数模型，根据碘海醇剂量和九点血药消失曲线下的面积计算GFR(9)。在254个数据点中，只有2.8%偏离曲线超过3倍CV。由10、30、120和300分钟时间点计算出的GFR(4)与GFR(9)相关性良好（r = 0.999），且无偏差（GFR(9)和GFR(4)的均值±标准差分别为59.3±36.3和59.4±36.0毫升/分钟/1.73平方米）。GFR(9)与单室GFR的关系遵循Brochner - Mortensen之前报道的二次方程，从而可以根据120和300分钟时间点计算GFR。该GFR(2)与GFR(9)相关性良好（r = 0.986）。根据Schwartz身高/肌酐公式估算的GFR与GFR(9)相关（r = 0.934），但每1.73平方米高估GFR 12.2毫升/分钟。由于尿液收集存在变异性（中位CV = 24%），尿碘海醇清除率与GFR(9)的相关性较差（r = 0.770）。使用四点碘海醇血浆消失法可以准确测量GFR（在大多数情况下，两点就足够）；估算的GFR和尿清除率的实用性较差。
