Association of Uric Acid, Urea and Creatinine with Body Mass Index, Age and Gender.

Abstract

Obesity is one of main metabolic diseases causes worldwide. This metabolic disorder contributes greatly to the significant proportion of the burden of renal damage and dysfunction. The aim of this study is to assess the effect of body mass index (BMI) in males and females of different age on kidneys functions indicated by serum uric acid, urea and creatinine concentrations. Serum uric acid, urea and creatinine was measured in a total of 240 healthy individuals (120 males and 120 females) aged 18-60 years. Analysis of variance (ANOVA) was used to evaluate the effect of age, sex and body mass index (BMI) on serum uric acid, urea and creatinine concentrations.A positive correlation was detected between BMI and serum uric acid in both males and females of different ages. Serum creatinine and urea levels were found to have a significant positive correlation with BMI only at age ≥45 years in both males (p =0.0098, p=0.0489) and females (p=0.0149, p=0.0487) respectively. When the interaction between sex and BMI was considered, statistically significant difference in serum uric acid levels was demonstrated in all age groups (p<0.0001). However, serum creatinine and urea levels showed no significant differences up to age of 45 years. At and above age of 45 years, statistically significant difference in both serum creatinine and urea levels (p<0.0056 and p<0.0054 respectively) were found. The morbidly obese males in all age groups showed uric acid levels that let them be diagnosed to have hyperuricemia (based on the reference ranges given by Fortress diagnostic limited 2011: males’ uric acid cut off 416.5 µmol/L and females 339 µmol/L). Whereas, only the morbidly obese females at age ≥45 years have uric acid level that indicates hyperuricemia. The morbidly obese females <20 years or 20-44 years seem to be at the border line of hyperuricemia. Our study indicates that there is a positive relationship between BMI and serum uric acid among healthy subjects. Obesity may potentially serve as a novel clinical indicator for identifying patients with hyperuricemia. We demonstrated a sex difference in the incidence of hyperuricemia which may reflect a sex difference in renal uric acid clearance. Our study also showed that serum creatinine level is significantly directly correlated with BMI at age of 45 years or above. BMI is an independent predictor of creatinine increase in adult aged 45 years or more. The prevention of obesity and weight control are exceptionally important in the protection of renal function