囊型蛋白酶抑制剂C(cystatin C)被推荐作为证实试验估算肾小球滤过率(eGFR)的一种方法，尤其是在需要更精确的估算以作出临床决策时。尽管基于肌酸酐和囊型蛋白(Creatinine and Cystatin)的eGFR(eGFRcr-cys)在研究中是最准确的估算，但在现实世界情况下，尤其是在基于肌酸酐(eGFRcr)和囊型蛋白C(eGFRcys)的eGFR不一致时，其是否准确仍然不确定。我们在瑞典斯德哥尔摩对6,185名成年人进行了测量静脉注射iohexol清除的GFR的参考，这些人同时也测量了肌酸酐、囊型蛋白C、和iohexol清除的9,404个值。我们评估了eGFRcr、eGFRcys和eGFRcr-cys与mGFR之间的表现，包括中位数偏差、P30和正确分类的GFR类别。我们将分析结果分为三个类别：eGFRcys比eGFRcr低20%以上(eGFRcyseGFRcr)。结果:在4,226个样本(样本总数的45%)中，eGFRcr和eGFRcys相似，三个估算公式表现相似。相比之下，当估算不一致时，eGFRcr-cys更准确。例如，当eGFRcyseGFRcr(样本总数的8%)时，中位数偏差分别为-4.5、8.4和1.4 ml/min/1.73m2。这些发现在患有心血管疾病、心力衰竭、糖尿病、肝病和癌症的个体中都是一致的。在临床实践中，当eGFRcr和eGFRcys差异较大时，eGFRcr-cys比eGFRcr或eGFRcys更准确。版权所有©2023年美国肾脏学会。

Cystatin C is recommended as a confirmatory test to estimate glomerular filtration rate (eGFR) when more precise estimates are needed for clinical decision-making. Although eGFR based on both creatinine and cystatin (eGFRcr-cys) is the most accurate estimate in research studies, it is uncertain whether this is true in real-world settings, particularly when eGFR based on creatinine (eGFRcr) and cystatin C (eGFRcys) are discordant.We included 6,185 adults referred for measured GFR using plasma clearance of iohexol in Stockholm, Sweden, who had 9,404 concurrent measurements of creatinine, cystatin C, and iohexol clearance. The performance of eGFRcr, eGFRcys and eGFRcr-cys was assessed against mGFR with median bias, P30, and correct classification of GFR categories. We stratified analyses within three categories: eGFRcys at least 20% lower than eGFRcr (eGFRcyseGFRcr).Results: eGFRcr and eGFRcys were similar in 4,226 (45% of) samples, and all three estimating equations performed similarly. In contrast, eGFRcr-cys was much more accurate in cases of discordance. For example, when eGFRcyseGFRcr (8% of samples), median biases were -4.5, 8.4, and 1.4 ml/min/1.73m2. Findings were consistent among individuals with cardiovascular disease, heart failure, diabetes mellitus, liver disease, and cancer.When eGFRcr and eGFRcys are highly discordant in clinical practice, eGFRcr-cys is more accurate than either eGFRcr or eGFRcys.Copyright © 2023 by the American Society of Nephrology.