Poggio Emilio D, Nef Patrick C, Wang Xuelei, Greene Tom, Van Lente Frederick, Dennis Vincent W, Hall Phillip M
Department of Nephrology and Hypertension, Cleveland Clinic Foundation, Cleveland, OH 44195, USA.
Am J Kidney Dis. 2005 Aug;46(2):242-52. doi: 10.1053/j.ajkd.2005.04.023.
Estimating glomerular filtration rate (GFR) in severely ill inpatients is clinically important for therapeutic interventions and prognosis, but notoriously difficult to do accurately. The Modification of Diet in Renal Disease (MDRD) equation and Cockcroft-Gault (CG) formula are widely used to estimate renal function in sick hospitalized patients; however, neither method has been validated in this setting.
Iodine 125-iothalamate clearances (iGFR) performed in 107 sick inpatients with renal dysfunction were compared with estimated GFRs (eGFRs) from the 6- and 4-variable MDRD (MDRD eGFR) and CG (CG eGFR) equations.
Mean serum creatinine (SCr) level was 3.5 +/- 2.0 mg/dL (309 +/- 177 micromol/L), and mean iGFR was 17.1 +/- 17.9 mL/min/1.73 m2 (0.29 +/- 0.30 mL/s/1.73 m2). Six-variable MDRD eGFR was 22.5 +/- 17.4 mL/min/1.73 m2 (0.38 +/- 0.29 mL/s/1.73 m2), 4-variable MDRD eGFR was 23.9 +/- 16.3 mL/min/1.73 m2 (0.40 +/- 0.27 mL/s/1.73 m2), and CG eGFR was 26.0 +/- 17.1 mL/min/1.73 m2 (0.43 +/- 0.29 mL/s/1.73 m2). Blood urea nitrogen (BUN)/SCr ratios greater than 20 were seen in 58% of patients. Overall, the CG and MDRD equations overestimated iGFR, with poor agreement. Overestimation of at least 25% of measured iGFR was seen in 63%, 67%, and 70% of all inpatients when using the 6-variable MDRD, 4-variable MDRD, and CG equations, respectively. Accuracy of eGFR within 50% of measured iGFR was 55% for the 6-variable MDRD equation, 49% for the 4-variable MDRD equation, and 40% for the CG formula. The performance of both methods deteriorated further in patients with a BUN/SCr ratio greater than 20.
Estimation equations are performed poorly compared with iGFR and are not reliable measures of actual level of function in sick hospitalized patients, especially those with a high BUN/SCr ratio. Although use of the 6-variable MDRD equation provides a better estimation of GFR, it still is unsuitable for clinical application in this population.
估计重症住院患者的肾小球滤过率（GFR）对于治疗干预和预后评估具有重要临床意义，但准确估算极为困难。肾脏病饮食改良（MDRD）方程和Cockcroft - Gault（CG）公式被广泛用于估计患病住院患者的肾功能；然而，这两种方法在这种情况下均未得到验证。
对107例肾功能不全的患病住院患者进行的碘125 - 碘他拉酸盐清除率（iGFR）与6变量和4变量MDRD（MDRD eGFR）以及CG（CG eGFR）方程估算的GFR（eGFR）进行比较。
平均血清肌酐（SCr）水平为3.5±2.0mg/dL（309±177μmol/L），平均iGFR为17.1±17.9mL/min/1.73m²（0.29±0.30mL/s/1.73m²）。6变量MDRD eGFR为22.5±17.4mL/min/1.73m²（0.38±0.29mL/s/1.73m²），4变量MDRD eGFR为23.9±16.3mL/min/1.73m²（0.40±0.27mL/s/1.73m²），CG eGFR为26.0±17.1mL/min/1.73m²（0.43±0.29mL/s/1.73m²）。58%的患者血尿素氮（BUN）/SCr比值大于20。总体而言，CG和MDRD方程高估了iGFR，一致性较差。在所有住院患者中，分别使用6变量MDRD、4变量MDRD和CG方程时，至少高估实测iGFR 25%的情况分别见于63%、67%和70%的患者。eGFR在实测iGFR的50%范围内的准确率，6变量MDRD方程为55%，4变量MDRD方程为49%，CG公式为40%。在BUN/SCr比值大于20的患者中，两种方法的表现进一步恶化。
与iGFR相比，估算方程表现不佳，对于患病住院患者，尤其是BUN/SCr比值高的患者，不是实际功能水平的可靠测量方法。尽管使用六变量MDRD方程对GFR的估算更好，但仍不适用于该人群的临床应用。
