Revista Cubana de Medicina Militar (Aug 2024)
New equations to estimate serum creatinine concentrations by the compensated Jaffé method
Abstract
Introduction: Serum creatinine measurements are usually made by the Jaffé kinetic method (alkaline picrate) but this method is inaccurate due to the presence of interferents. Objective: Design equations that allow correcting the serum creatinine values ??measured by the Jaffé kinetic method. Methods: Experimental methodological study. Serum creatinine values ??obtained from subjects who underwent laboratory tests at the Institute of Nephrology and Pediatrics of Centro Habana, Havana, Cuba were used; by three methods: IDMS-traceable Jaffé kinetic (gold standard), automated Jaffé kinetic, and manual Jaffé kinetic. SPSS 21.0 software was used to perform frequency analysis, Student's t test for comparison of means, Pearson's correlation, multiple regression, and residue analysis. Simple linear regression was performed to obtain the correction equations. Results: 449 subjects were included. Four correction equations were created according to the measurement method and creatinine levels. It was found: Student's t test significant in both comparisons, strong Pearson correlations with r 2 above 0.75. Mean and standard deviation of creatinine once corrected were similar to the gold standard, Pearson's correlation of 0.918 and 0.889 pre-correction, and 0.996 and 0.995 post-correction for automated and manual methods, respectively. Conclusions: Four equations are presented for the correction of serum creatinine concentrations, measured by the Jaffé kinetic method, corresponding to creatinine values lower than 1 mg/dl, and equal or greater than 1 mg/dl, both for the manual and automated methods.
