Evaluation of renal function and proteinuria based on mass health examinations in young Japanese obese adults

Although obesity is recognized to be a risk factor for chronic kidney disease (CKD), few studies have reported the association between obesity and CKD in the young population. We investigated the relationship between obesity and renal function including proteinuria in young Japanese. This cross-sectional study consisted of 16,031 men and 5,746 women aged from 20 to 39 years who received health examinations. The subjects were stratified into four age groups (20-24, 25-29, 30-34, and 35-39 years) or into four groups based on the number of risk factors (hypertension, hyperglycemia, dyslipidemia, and hyperuricemia). The relationship between obesity and risk factors and the relationship between obesity and estimated glomerular filtration rate (eGFR) were analyzed. There were no significant differences in eGFR between obese and nonobese groups, except in the male 35-39 years age group. Body mass index (BMI) in both men and women increased with increase in number of risk factors (P < 0.001). Multivariate analysis revealed that hypertension, hyperglycemia, dyslipidemia, and hyperuricemia were independently associated with obesity. Obesity and the risk factors were independently associated with proteinuria. The present study indicated that obesity was an independent risk factor for proteinuria in healthy subjects younger than 40 years of age. The other risk factors were independently associated with obesity. These findings suggest that obesity causes proteinuria concomitantly with other risk factors such as hypertension, diabetes, and dyslipidemia in young adults.