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

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