Department of Inflammation Biology, Faculty of Life Sciences and Medicine, King's College London, London, UK
King's Kidney Care, King's College Hospital, London, UK.
J Clin Pathol. 2023 Jul;76(7):442-449. doi: 10.1136/jcp-2023-208887. Epub 2023 May 10.
Accurate diagnosis, classification and risk stratification for chronic kidney disease (CKD) allow for early recognition and delivering optimal care. Creatinine-based glomerular filtration rate (GFR), urinary albumin: creatinine ratio (UACR) and the kidney failure risk equation (KFRE) are important tools to achieve this, but understanding their limitations is important for optimal implementation.When accurate GFR is required (eg, chemotherapy dosing), GFR is measured using an exogenous filtration marker. In routine clinical practice, in contrast, estimated GFR (eGFR) from serum creatinine (SCr), calculated using the enzymatic method±UACR, is recommended. Limitations of SCr include non-GFR determinants such as muscle mass, diet and tubular handling. An alternative or additional endogenous filtration marker is cystatin C, which can be used alongside SCr for confirmatory testing of CKD. However, its role in the UK is more limited due to concerns regarding false positive results.The recommended creatinine-based eGFR equation in the UK is the CKD Epidemiology Collaboration 2009 equation. This was recently updated to a race-neutral 2021 version and demonstrated reduced bias in people of Black ethnicity, but has not been validated in the UK. Limitations are extremes of age, inaccuracy at greater GFRs and reduced generalisability to under-represented ethnicity groups.The KFRE (based on age, sex, SCr and UACR) has recently been developed to help determine 2-year and 5-year risk of progression to end-stage kidney disease. It has been validated in over 30 countries and provides meaningful quantitative information to patients. However, supporting evidence for their performance in ethnic minority groups and kidney diseases such as glomerulonephritis remains modest.In conclusion, early identification, risk stratification of kidney disease and timely intervention are important to impact kidney disease progression. However, clinician awareness of the limitations and variability of creatinine, cystatin C and the eGFR equations, is key to appropriate interpretation of results.
准确的诊断、分类和慢性肾脏病（CKD）的风险分层可以实现早期识别并提供最佳的护理。基于肌酐的肾小球滤过率（GFR）、尿白蛋白与肌酐比值（UACR）和肾衰竭风险方程（KFRE）是实现这一目标的重要工具，但了解其局限性对于最佳实施至关重要。当需要准确的 GFR 时（例如，化疗剂量），使用外源性滤过标志物测量 GFR。相比之下，在常规临床实践中，建议使用血清肌酐（SCr）计算的酶法±UACR 估计肾小球滤过率（eGFR）。SCr 的局限性包括非 GFR 决定因素，如肌肉量、饮食和肾小管处理。替代或额外的内源性滤过标志物是胱抑素 C，可以与 SCr 一起用于 CKD 的确认性检测。然而，由于对假阳性结果的担忧，其在英国的作用更为有限。英国推荐的基于肌酐的 eGFR 方程是 CKD 流行病学合作组 2009 年方程。最近，该方程更新为种族中立的 2021 年版本，在黑人种族中显示出较低的偏差，但尚未在英国得到验证。其局限性包括年龄极端、在较高 GFR 时不准确以及对代表性不足的种族群体的概括性降低。KFRE（基于年龄、性别、SCr 和 UACR）最近被开发用于帮助确定 2 年和 5 年进展为终末期肾病的风险。它已在 30 多个国家得到验证，并为患者提供了有意义的定量信息。然而，关于其在少数族裔和肾小球肾炎等肾脏疾病中的性能的支持证据仍然有限。总之，早期识别、肾脏病的风险分层和及时干预对于影响肾脏病的进展非常重要。然而，临床医生对肌酐、胱抑素 C 和 eGFR 方程的局限性和可变性的认识是正确解释结果的关键。
