C-terminal agrin fragment as a novel biomarker of kidney function in obese children and adolescents.

Abstract Background: Obesity is a global health problem which has a negative impact on many organs, including kidneys. Studies, conducted mainly in obese adults have confirmed that obesity is associated with increased risk of chronic kidney disease (CKD) development. So, the detection of early kidney lesions is crucial for the patients. The aim of the study was to determine the usefulness of serum C-terminal fragment of agrin (t-CAF) and cystatin C levels along with hyperfiltration as indicators of kidney function damage in obese children and their relationship with the severity of obesity. Material and methods: 125 children and adolescents with simple obesity and 33 healthy peers with normal body mass were enrolled. Patients were divided into two groups, depending on SDS BMI values (below and over 4). The serum concentration of t-CAF and cyststic C were assessed by ELISA, eGFR was calculated using Schwartz formula Results : t-CAF and cystatin C as well as eGFR were significantly higher in obese children compared to healthy peers (p< 0.000). However, there were no differences in t-CAF, cystatin C and eGFR between the obese groups. Albumin excretion did not distinguish obese groups from the controls. Conclusions: In obese children without overt signs of kidney damage, hyperfiltration promotes early kidney dysfunction. This is supported by elevated serum cystatin C and t-CAF levels. t-CAF seems to be a better biomarker than cystatin C due to its potential role in adipogenesis. The degree of obesity in children without significant metabolic disorders does not affect kidney function but further studies are needed to confirm it.