The incidence of non-alcoholic fatty liver disease (NAFLD) is increasing with obesity, and it is believed that ongoing inflammation in obesity and alterations in the enterohepatic axis contribute to this process. This study aimed to determine the role of fecal calprotectin (FCP) as an inflammatory biomarker in course of obesity and NAFLD.

Obesity is a significant public health issue worldwide. With the increasing prevalence of obesity, the prevalence of metabolic syndrome in adolescents is also on the rise. Non-alcoholic fatty liver disease (NAFLD), a major cause of chronic liver disease, is the hepatic component of metabolic syndrome. The prevalence of NAFLD is not precisely known, but in some studies, it is between 22.5% and 52.8% in children with obesity, constituting 2.6% of all children. Although the mechanisms involved in the development of obesity-related metabolic complications and NAFLD are not well understood, it is believed that intestinal inflammation, changes in the microbiota, and alterations in the gut-liver axis (GLA) may play a role in the development of low-grade chronic inflammation in NAFLD associated with obesity. Fecal calprotectin (FCP), which has become increasingly important in demonstrating intestinal inflammation in recent years, is a widely used test, particularly in the diagnosis and monitoring of inflammatory bowel disease and various gastrointestinal disorders. In our study, the utility of FCP as an inflammatory biomarker in the course of NAFLD in obese adolescents has been investigated. The study was approved by our hospital's ethics committee in 15.11.2022 and another ethics committee approval was taken in 08.06.2023 for title change of study. This study conducted under the Helsinki Declaration.

Inclusion Criteria:

• 10-18 years old healthy adolescents for control group
• Children aged 10-18 years without any additional diseases, BMI>2 SD, no hepatosteatosis detected by ultrasonography (USG), and alanine aminotransferase (ALT) levels within normal limits were included in the obese group
• Children aged 10-18 years without any additional diseases, BMI>2 SD, Hepatosteatosis detected by ultrasonography (USG), and alanine aminotransferase (ALT) levels higher than normal limits adjusted for gender were included in the obese + NAFLD group

Exclusion Criteria:

• Diseases other than obesity and NAFLD