Body mass index and implications for pediatric kidney health: a cross-sectional study with urinary biomarkers

Background Extremes of unhealthy body weight, particularly obesity, are known to increase the risk of chronic kidney diseases. However, the current knowledge of kidney health outcomes associated with unhealthy body weight remains incomprehensive, especially in pediatrics. Therefore, the present study aimed to evaluate body mass index (BMI) and its potential associations with kidney health in a selected subset of school students in Sri Lanka. Methods This cross-sectional study was conducted among students of both sexes in the range of 11–18 years of age ( N = 1078) in education zones with no reported cases of chronic kidney disease of uncertain etiology. Based on sex- and age-specific BMI percentiles (LMS method), the participants were classified into five BMI groups (severely thin, thin, healthy, overweight, and obese) for measurement of urinary biomarkers of kidney injury: kidney injury molecule (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), and albumin creatinine ratio (ACR). Results The median urinary levels of NGAL, ACR, and particularly KIM-1, which is a more sensitive indicator of kidney injury, showed no significant differences across the BMI strata. Importantly, moderate correlations of BMI with KIM-1 and NGAL were identified in severely thin girls. Conclusions According to the present study, these findings do not produce plausibly strong evidence to establish a potential association of BMI with altered kidney function in the studied pediatric communities. Particularly, a likelihood of abnormal kidney health outcomes associated with undernutrition is apparent in severely thin girls. However, in-depth studies are warranted to develop a comprehensive understanding of the associations of nutritional status with pediatric kidney health in Sri Lanka. Graphical Abstract A higher resolution version of the Graphical abstract is available as Supplementary information