肾小球滤过率对急慢性肾脏病患者溶质及电解质肾脏排泄分数的影响

Effect of glomerular filtration rate on renal excretion fraction of solute and electrolyte in patients with acute and chronic kidney disease

目的:探索慢性肾脏病(CKD)中溶质及电解质肾脏排泄分数(FEx)和肾功能的关系,比较CKD和急性肾损伤(AKI)患者FEx的差别。方法:选取2020年1月至2022年8月在国家肾脏疾病临床医学研究中心诊治的具有完整血尿生化结果的CKD或AKI患者,分析估算的肾小球滤过率(e GFR)和FEx的关系,倾向得分匹配后比较CKD和AKI中FEx的差异。结果:研究纳入261例CKD和53例AKI患者。多数FEx随CKD进展进行性升高;钠、钾、氯、磷和尿酸的排泄分数(FENa、FEK、FECl、FEP和FEUA)与e GFR密切相关,并且建立了相对排泄分数(RFE)与e GFR的回归方程。AKI患者在e GFR-FEx散点图中与CKD患者表现出大致相同的趋势。倾向得分匹配后发现e GFR≥60 m L/(min·1.73m^(2))和<60 m L/(min·1.73m^(2))时,CKD和AKI之间有显著差异的分别为尿素排泄分数(FEUN)和FEUA。FEUN<12.95%[曲线下面积(AUC)0.65,灵敏度70.0%,特异度57.1%]和FEUA>11.41%(AUC 0.74,灵敏度75.8%,特异度73.5%)分别为e GFR≥60 m L/(min·1.73m^(2))和<60 m L/(min·1.73m^(2))时诊断AKI的最佳截断值。结论:无论CKD还是AKI患者,e GFR对FEx均有显著影响,大多数FEx随e GFR降低而进行性升高。e GFR≥60 m L/(min·1.73m^(2))时FEUN<12.95%和e GFR<60 m L/(min·1.73m^(2))时FEUA>11.41%对区分CKD和AKI有诊断价值。

Objective:To investigate the relationship of renal fractional excretion of solutes or electrolytes(FEx)and glomerular filtration rate(GFR)in chronic kidney disease(CKD)patients,and compare FEx in CKD patients with in acute kidney injury(AKI).Methodology:From January 2020 to August 2022,patients diagnosed as CKD or AKI in National Clinical Research Center of Kidney Diseases were retrospectively screened of whom with full records of blood and urine biochemical tests.Estimated GFR(e GFR)and fractional excretion of sodium(FENa),potassium(FEK),chloride(FECl),phosphorus(FEP),calcium(FECa),urea(FEUN)and uric acid(FEUA)were calculated.The relationship between FEx and e GFR in CKD was analyzed.Comparisons of FEx in AKI and CKD patients were made after propensity score matching(PSM).Results:261 CKD patients and 53 AKI patients were included in the study.Most of FEx increases significantly with the progression of CKD stage.A close relationship of FEx(FENa、FEK、FECl、FEP and FEUA)and e GFR was found.The ratio of individual FEx and the mean value of FEx in CKD stage 1 patients was calculated as relative FEx(RFEx),and nonlinear curve-fitting equations of e GFR-RFEx were established in Na,K,Cl,P,and UA.Scatter plots of e GFR-FEx in AKI patients show similar patterns as seen in CKD patients.With a much lower e GFR in AKI group,significant differences were found in all FEx between AKI and CKD group.After PSM focusing on sex,age and e GFR,a significant difference between AKI and CKD group was only seen in FEUN in patients with e GFR≥60 m L/(min·1.73m^(2)),and FEUA in patients with e GFR<60 m L/(min·1.73m^(2)).The optimal cut-off value to distinguish AKI from CKD in patients with e GFR≥60 m L/(min·1.73m^(2))is FEUN<12.95%(AUC 0.65,sensitivity 70.0%,specificity 57.1%);while in patients with e GFR<60 m L/(min·1.73m^(2)),it is FEUA>11.41%(AUC 0.74,sensitivity 75.8%,specificity 73.5%).Conclusion:e GFR has a distinct impact on FEx,with most of FEx increase progressively along with the decline of e GFR regardless of CKD or AKI.It has a diagnostic value for FEUN in patients with e GFR≥60 m L/(min·1.73m^(2))and for FEUA in patients with e GFR<60 m L/(min·1.73m^(2))to distinguish AKI from CKD.