Abstract:

Objective To evaluate the clinical application value of an improved point-of-care testing （POCT）-based modified time-resolved fluoroimmunoassay（TRFIA） for rapid quantitative determination of urinary albumin/creatinine ratio（ACR）. Methods Totally，200 kidney disease patients and 20 healthy subjects from Shanghai Jiao Tong University School of Medicine Affiliated Tongren Hospital were enrolled from January to April 2024，and the random urine specimens were collected. Estimated glomerular filtration rate （eGFR） was used for kidney injury staging （G1，G2，G3 and above）. Urinary albumin （Alb） and creatinine （Cr） were determined by both Hitachi 3500 and LTRIC-600，and urinary ACR was calculated. Methodological evaluation of LTRIC-600 was performed，and urinary Cr in 40 selected patients was verified by mass spectrometry. Receiver operating characteristic （ROC） curve was used to evaluate the efficacy of LTRIC-600 in determining ACR for differentiating kidney injury between G1 and G2 stages. Results LTRIC-600 showed good performance in determining urinary Alb and Cr. Urinary ACR consistency between LTRIC-600 and Hitachi 3500 was good （kappa=0.89）. Good correlations were found between the 2 methods for urinary Alb （r=0.89），Cr （r=0.78） and ACR （r=0.86）（P<0.05）. Mass spectrometry also showed good correlations with both the 2 methods （r=0.89 and 0.83）. No significant ACR differences were seen between LTRIC-600 and Hitachi 3500 across kidney injury stages （P>0.05）. LTRIC-600 had an area under curve （AUC） of 0.872 for distinguishing G1 from G2. Conclusions LTRIC-600 demonstrates high accuracy and consistency in ACR determination，making it suitable for chronic kidney disease screening and monitoring，with potential in primary and home-care settings.

Key words: Albumin/creatinine ratio, Time-resolved fluoroimmunoassay, Point-of-care testing