Department of Pharmacy Practice and Science, University of Arizona R. Ken Coit College of Pharmacy, Tucson, AZ, USA.
Am J Health Syst Pharm. 2023 Jun 7;80(12):712-718. doi: 10.1093/ajhp/zxad058.
Creatinine-based estimates of glomerular filtration rate (GFR) have been the standard for classifying kidney function and guiding drug dosing for over 5 decades. There have been many efforts to compare and improve different methods to estimate GFR. The National Kidney Foundation recently updated the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations without race for creatinine (CKD-EPIcr_R) and creatinine and cystatin C (CKD-EPIcr-cys_R), and the 2012 CKD-EPI equation based on cystatin C (CKD-EPIcys) remains. The focus of this review is to highlight the importance of muscle atrophy as a cause for overestimation of GFR when using creatinine-based methods.
Patients with liver disease, protein malnutrition, inactivity, denervation, or extensive weight loss may exhibit markedly lower creatinine excretion and serum creatinine concentration, leading to overestimation of GFR or creatinine clearance when using the Cockcroft-Gault equation or CKD-EPIcr (deindexed). In some cases, estimated GFR appears to exceed the physiological normal range (eg, >150 mL/min/1.73 m2). Use of cystatin C is recommended when low muscle mass is suspected. One would expect discordance between the estimates such that CKD-EPIcys < CKD-EPIcr-cys < CKD-EPIcr ≈ Cockcroft-Gault creatinine clearance. Clinical evaluation can then occur to determine which estimate is likely accurate and should be used for drug dosing.
In the setting of significant muscle atrophy and stable serum creatinine levels, use of cystatin C is recommended, and the resulting estimate can be used to calibrate interpretation of future serum creatinine measurements.
基于肌酐的肾小球滤过率（GFR）估计值在过去 50 多年来一直是分类肾功能和指导药物剂量的标准。人们一直在努力比较和改进不同的 GFR 估计方法。最近，国家肾脏基金会更新了没有种族差异的慢性肾脏病流行病学合作（CKD-EPI）肌酐方程（CKD-EPIcr_R）和肌酐和胱抑素 C 方程（CKD-EPIcr-cys_R），2012 年基于胱抑素 C 的 CKD-EPI 方程（CKD-EPIcys）仍然存在。本综述的重点是强调肌肉萎缩作为使用基于肌酐的方法时高估 GFR 的原因的重要性。
患有肝脏疾病、蛋白质营养不良、不活动、去神经支配或广泛体重减轻的患者可能表现出明显较低的肌酐排泄和血清肌酐浓度，导致使用 Cockcroft-Gault 方程或 CKD-EPIcr（去指数化）时高估 GFR 或肌酐清除率。在某些情况下，估计的 GFR 似乎超过了生理正常范围（例如，>150 mL/min/1.73 m2）。当怀疑肌肉量低时，建议使用胱抑素 C。预计这些估计值之间会存在不一致，即 CKD-EPIcys < CKD-EPIcr-cys < CKD-EPIcr ≈ Cockcroft-Gault 肌酐清除率。然后可以进行临床评估，以确定哪个估计值可能准确，应用于药物剂量。
在存在明显肌肉萎缩和稳定的血清肌酐水平的情况下，建议使用胱抑素 C，并且可以使用由此产生的估计值来校准对未来血清肌酐测量的解释。
