Abstract Background Creatinine is widely used in diagnostic medicine as a primary renal marker. Clinical laboratory measurement of serum creatinine is not standardized, and the RI varies slightly between different manufacturers. Roche brings as reference ranges 0.5–0.9 mg/DL for women and 0.7–1.2 mg/dL for men. After clinical manifestations of elevated female results without clinical correspondence, the laboratory proceeded with reevaluation of RI. Methods We retrospectively studied the creatinine results of the laboratory database of samples run from January to October 2022 in two different technical areas in Brazil (São Paulo and Rio de Janeiro). The laboratory platform was Roche® 502/702, Jaffe method to creatinine. The LabRI tool was used with parametric, non-parametric, and robust statistical treatments to exclude outliers and algorithms in the R Language and latent abnormal values of outpatient patients. The partitions proposed were gender (male and female), age (18–60 years old and over 60 years old). The proposed RI for verification were those proposed by Rosenfeld, LG et al in REV BRAS EPIDEMIOL 2019; 22 (SUPPL2):E190002.SUPL.2 - F: 0.5–0.9 and M: 0.7–1.2. Exclusion criteria were patients with urea >48.5 mg/dL, glycemia >200 mg/dL, 24 h proteinuria >150 mg/24 h, LDL > 130 mg/dL, uric acid > 130 mg/dL, anti-nucleus positive factor, as well as clinical data compatible with chronic renal failure or dialysis, hypertension and diabetes. Results After exclusion, retrieved 225 181 individuals 52% female. Between the different sites, the results of the partitions did not undergo significant changes. For women in both age partitions, the values did not vary significantly. For men, there was no significant variation in the lower limit of IR, and we had a variation of 0.20 (18–60: 0.69–1.31 and >60: 0.69–1.41) in the upper limit, mainly for the age partition >60 years old, below the 95% confidence interval of the proposed references. Conclusions The adoption of the Roche IR and the Brazilian article was approved for the female gender (0.5–0.9) with 118 100 individuals, and a new IR was defined for the male gender (0.7–1.2) with 107 081 adult individuals, including the elderly over 60 years old, for both genders.