RESUMO
Objective To compare the consistency between single-(I-GFR-SS) and dual-(I-GFR-DS) sample methods with three-sample method (I-GFR-TS) of iohexol plasma clearance in chronic kidney disease (CKD) patients for choosing the optimizing project of glomerular filtration rate (GFR) measurement.Methods The multiple-sample methods were performed in 174 patients with CKD admitted to the Department of Nephrology,Shanghai Ruijin Hospital from August 2017 to July 2018.Plasma concentrations of iohexol were measured three times at different time points after receiving 5 ml iohexol (300 g/L) intravenous injection,according to estimated GFR (eGFR) grouping.The first blood sample was collected at 2 hours,and the time for the last sample was delayed from 4 hours to 6 hours with reduction of eGFR.The synchronized Gates (99mTc-Gates-GFR) method was detected as control.With I-GFR-TS as the golden standard,the accuracies of I-GFR-DS,I-GFR-SS and 99mTc-Gates-GFR were compared.Results The median differences of I-GFR-DS,I-GFR-SS and 99mTc-Gates-GFR in overall patients were-0.15,-1.00,6.76 ml· min-1· (1.73 m2)-1 comparing with I-GFR-TS;P10(percentage of the GFRmeasurements that was within 10％ of the standard method) were 95.4％,74.1％,28.7％,and P30 were 100％,93.7％,72.4％ separately.In the patients with eGFR ＜ 30 ml· min-1· (1.73 m2)-1,I-GFR-SS was more accurate when last point collecting extended to 6 h from 4 h [P10:43.5％ vs 17.4％,P=0.055;P30:73.9％ vs 43.5％,P＜0.05].Conclusions The dual-sample plasma clearance of iohexol is recommended in clinical practice,and the single-sample method can be a secondary option because of its slightly poor accuracy but more convenient.Sample-collection protocol should be adjusted according to eGFR especially in moderate-to-severe CKD patients.The Gates method is not recommended.