Background: Obesity is a well-established risk factor for the development of renal disease in adults. In children the contribution of obesity to renal dysfunction is less well understood. We investigated the prevalence of renal dysfunction in an obese paediatric cohort with the aim of understanding which anthropometric characteristics would be better indicators of risk in a clinical setting.
Methods: Patients were enrolled into the Childhood Overweight Biorepository of Australia (COBRA) study, from the multidisciplinary weight management service at the Royal Children’s Hospital in Melbourne (n=297, M 47%, mean BMI z-score 2.47, mean BMI 35.74±6.38, mean age 11 years). Extensive clinical, pathology and biochemistry data were collected. Renal function was assessed by eGFR, urinary albumin to creatinine ratio (ACR), urinary cystatin C, osteopontin, β2 microglobulin and NGAL. Statistical modelling was used to assess each measurement against anthropometric data; BMI z-score, BMI and total body fat %.
Results: BMI, but not BMI z-score correlated with urinary Cystatin C/creatinine ratio (r=0.249, p=0.039), urinary osteopontin (r=0.362, p=0.005) systolic (r=0.489, p<0.001) and diastolic blood pressure (r=0.271, p=0.36). Calculations for glomerular filtration correlated with BMI z-score (eGFR, r=-0.409, p=0.017, ACR r=0.294, p=0.017). In multiple regression modelling age and BMI z-score accounted for 27% of the variation in eGFR ratio (R=0.572, p<0.01).
Conclusion: Paediatric obesity is a risk factor for the development of renal disease, and hence should be included in the common assessments of co-morbidities. Total BMI rather than BMI z-scores may better predict early renal disease.