Division of Nephrology, Department of Medicine, University of California, San Francisco, San Francisco, CA 94143-0532, USA.
J Am Soc Nephrol. 2011 Oct;22(10):1931-7. doi: 10.1681/ASN.2010101077. Epub 2011 Sep 15.
Although many assume that measurement of glomerular filtration rate (GFR) using a marker such as iothalamate (iGFR) is superior to equation-estimated GFR (eGFR), each of these methods has distinct disadvantages. Because physicians often use renal function to guide the screening for various CKD-associated complications, one method to compare the clinical utility of iGFR and eGFR is to determine the strength of their association with CKD-associated comorbidities. Using a subset of 1214 participants in the Chronic Renal Insufficiency Cohort (CRIC) Study, we determined the cross-sectional associations between known complications of CKD and iGFR, eGFR estimated from serum creatinine (eGFR_Cr), and eGFR estimated from cystatin C (eGFR_cysC). We found that none of the measures of renal function strongly associated with CKD complications and that the relative strengths of associations varied according to the outcome of interest. For example, iGFR demonstrated better discrimination than eGFR_Cr and eGFR_cysC for outcomes of anemia and hemoglobin concentration; however, both eGFR_Cr and eGFR_cysC demonstrated better discrimination than iGFR for outcomes of hyperphosphatemia and phosphorus level. iGFR and eGFR had similar strengths of association with hyperkalemia/potassium level and with metabolic acidosis/bicarbonate level. In conclusion, iothalamate measurement of GFR is not consistently superior to equation-based estimations of GFR in explaining CKD-related comorbidities. These results raise questions regarding the conventional view that iGFR is the "gold standard" measure of kidney function.
虽然许多人认为使用碘海醇（iGFR）等标志物测量肾小球滤过率（GFR）优于方程估算的 GFR（eGFR），但这两种方法都有明显的缺点。由于医生通常使用肾功能来指导各种 CKD 相关并发症的筛查，因此比较 iGFR 和 eGFR 临床实用性的一种方法是确定它们与 CKD 相关合并症的关联强度。我们使用慢性肾功能不全队列（CRIC）研究的 1214 名参与者的一个子集，确定了已知 CKD 并发症与 iGFR、血清肌酐估算的 eGFR（eGFR_Cr）和胱抑素 C 估算的 eGFR（eGFR_cysC）之间的横断面关联。我们发现，肾功能的所有这些指标都与 CKD 并发症没有很强的关联，并且关联的相对强度因感兴趣的结果而异。例如，iGFR 与贫血和血红蛋白浓度等结果的相关性优于 eGFR_Cr 和 eGFR_cysC；然而，对于高磷血症和磷水平等结果，eGFR_Cr 和 eGFR_cysC 的判别能力均优于 iGFR。iGFR 和 eGFR 与高钾血症/钾水平和代谢性酸中毒/碳酸氢盐水平的关联强度相似。总之，碘海醇测量 GFR 并不总是优于基于方程的 GFR 估算值来解释 CKD 相关的合并症。这些结果对 iGFR 是肾功能“金标准”测量的传统观点提出了质疑。
