To analyze factors that influence serum Urea and creatinine (Cr) of adults in Foshan, and establish a preliminary reference interval for adult serum Urea and Cr.

A total of 10 412 persons who conducted physical examination between March 1 and August 31, 2021 at the physical examination center of the Foshan Fosun Chancheng Hospital were randomly selected. The serum Urea, Cr, fasting plasma glucose (FPG), total cholesterol (TC), triglyceride (TG), high density lipoprotein (HDL-C), low density lipoprotein (LDL-C) and uric acid (UA) were measured by Beckman AU5800 automatic biochemical analyzer. The distribution characteristics of Urea and Cr, as well as the mutual influence of gender, age, FPG, TC, TG, HDL-C, LDL-C, and UA on Urea and Cr were analyzed. The medical reference intervals of serum Urea and Cr were established.

Laboratory reference intervals of FPG, TC, TG, HDL-C, LDL-C, and UA were used to screen research subjects. In addition, subjects with outliers in Urea and Cr were also excluded. A total of 2267 in 10 412 subjects were eligible for this study. Analysis of 2267 subjects showed that the reference interval of serum Urea and Cr in Foshan can be subdivided by the age of 60 in male, and the age of 50 in female. The reference interval of serum Urea in male >60 years: 4.61 (2.9, 7.21) mmol/L, in male ≥60 years: 5.42 (3.35, 8.46) mmol/ L; in female <50 years: 3.89 (2.43, 6.15) mmol/L, in female ≥50 years: 4.76 (2.84, 8.06) mmol/L; the reference interval of serum Cr in male <60 years: 83 (65, 104) μmol/L, in male ≥60 years: 84 (63, 122) μmol/L; in female <50 years: 58 (45, 74) μmol/L, in female ≥50 years: 63 (46, 92) μmol/L.

The reference intervals for serum urea and creatinine of healthy adults in Foshan are not the same among different genders and ages. Reference intervals should be set up according to gender and age.