Prevalence and factors related to urinary albumin excretion in obese youths.

OBJECTIVE

The aim of the present study is to assess whether obesity is associated with urinary albumin excretion and what the main determinants are.

METHODS

One hundred and thirty-four obese white children and adolescents of both sexes, ranging from 9 to 18 years of age (mean age 12.6 ± 2.0), were included in the study. Obesity was defined on the basis of a threshold BMI z-score of more than 2 (Cole's LMS method) and overweight with a BMI from the 85th to 95th percentile. Office blood pressure was measured using a mercury sphygmomanometer. Urinary albumin excretion was measured in the first voiding urine of the morning and expressed in albumin/creatinine ratio in mg/g. Reproducibility of the urinary albumin excretion was studied by the Bland and Altman technique in a subgroup. Triglycerides, uric acid, fasting glucose and insulin were measured and the homeostatic model assessment (HOMA) index was calculated.

RESULTS

The prevalence of microalbuminuria was 2.4%. No differences in the prevalence of microalbuminuria were observed when the different groups of obesity degree were compared (0, 2.2 and 0% in overweight, moderate and severe obese, respectively). A significant relationship emerged between the Log urinary albumin excretion and BMI z-score, waist circumference, Log triglycerides, fasting insulin and HOMA index, adjusted by age and sex. In a multiple regression analysis, the main determinants of Log urinary albumin excretion were sex, waist circumference and Log triglycerides. In 17% of the individuals who fulfil criteria for metabolic syndrome, urinary albumin excretion was significantly higher than those without.

CONCLUSIONS

The prevalence of elevated urinary albumin excretion is not prominent in obese children, and when it is increased, it depends mainly on metabolic factors.