High free leptin index as the risk factor for childhood obesity in Indonesia: A case-control study.

Identifying the risk factors is critical in preventing childhood obesity. Leptin concentration is elevated in obesity. High serum leptin levels are believed to reduce soluble leptin receptor (sOB-R) concentrations and are associated with leptin resistance. The free leptin index (FLI) is a biomarker of leptin resistance and the status of leptin action. This study aims to investigate the association between leptin, sOB-R, and FLI with measurements to diagnose obesity in children, such as BMI, waist circumference and waist-to-height ratio (WHtR). We conducted a case-control study in 10 elementary schools in Medan, Indonesia. The case group was children with obesity, while the control group was children with normal BMI. Leptin and sOB-R levels were measured from all the subjects using the ELISA method. Logistic regression analysis was employed to determine which factors were predictor variables of obesity. A total of 202 children between 6 and 12 years old were recruited for this study. Children with obesity showed significantly higher leptin levels and FLI and lower SOB-R levels FLI (p < .05) than control. The cut-off for WHtR in this study was 0.499 (sensitivity 90% and specificity 92.5%). Children with higher leptin levels had a higher risk of obesity based on BMI, waist circumference, and WHtR values.

A highly sensitive, simple, and fast gas chromatography-mass spectrometry method for the quantification of serum short-chain fatty acids and their potential features in central obesity.

Short-chain fatty acids (SCFAs) are the main gut microbe metabolites, which have no more than six carbons. SCFAs are an emerging biomarker in metabolic diseases, including central obesity. Commonly, SCFAs are measured in fecal samples, where they are highly abundant, but here they do not reflect direct interactions with related organs. Serum SCFAs are assumed to be more associated with metabolic disease than fecal SCFAs, albeit at very low concentrations. The aim of the present study is to develop a highly sensitive, simple, and fast method for measuring six SCFAs in the serum by gas chromatography-mass spectrometry (GCMS). The serum is mixed with meta-phosphoric acid and 2,2-dimethylbutyric acid, followed by homogenization and centrifugation. Supernatant is then injected into the fused silica capillary column. The method is linear from 0.12-500 µmol/L for all SCFAs with an accuracy of 90-117%. The total coefficient of variation for precision ranges from 3.8 to 14.1%. A preliminary study is performed with 32 centrally obese subjects and 17 lean subjects. The mean values of all SCFAs, including acetic, propionic, isobutyric, butyric, isovaleric, and valeric acid, in the centrally obese subjects are significantly higher compared with lean subjects. A significant correlation also exists between all SCFAs, with the waist circumference indicating that serum SCFAs have potential features with respect to metabolic diseases, especially central obesity. The validated GCMS method provides highly sensitive, fast, simple, and reliable SCFA quantitation in the serum and demonstrates the potential features of circulating SCFAs in central obesity.