Liver Fibrosis Is Positively and Independently Associated with Leptin Circulating Levels in Individuals That Are Overweight and Obese: A FibroScan-Based Cross-Sectional Study.

Background: Metabolic dysfunction-associated steatotic liver disease (MASLD) is strongly correlated with the severity of obesity, and the extent of liver fibrosis is associated with a higher risk of liver-related complications, cardiovascular events, and overall mortality. Leptin circulating levels are directly correlated with the amount of adipose tissue. Aims: In the present study, we investigated the association between circulating leptin levels and liver steatosis and fibrosis. Methods: Eighty-six patients (41.7 ± 12.6 yrs, 35 men, 41%), naïve to medications, who attended the Nutrition Center for the Research and Care of Obesity and Metabolic Diseases at the National Institute of Gastroenterology "Saverio de Bellis" for weight management, were cross-sectionally evaluated. Demographic, anthropometric, clinical, and laboratory data were collected and analyzed. All patients underwent liver ultrasonographic assessment by FibroScan to diagnose liver steatosis (controlled attenuation parameter, CAP > 275 dBm) and fibrosis (liver stiffness measurement, LSM > 8.2 kPa). Results: Sixty-three individuals (73.3%) had liver steatosis, and 17 (19.8%) had liver fibrosis. The mean leptin levels were 22.3 ± 14.1 ng/mL, while the BMI and waist circumference were 36.7 ± 7.2 kg/m2 and 114.5 ± 16.4 cm, respectively. CAP values exhibited no correlation with leptin (r = 0.09, p = 0.436), while a significant connection was seen between leptin and LSM (β = 0.065; p = 0.038). Specifically, for each unit increase in leptin, LSM values were varied by +0.065 units (p = 0.038). This association was independent of gender, age, insulin resistance, adiponectin, RBP4, and visfatin. This is the first study showing these results by using FibroScan assessment in patients naïve to medications. Conclusions: Circulating leptin concentrations are independently correlated with hepatic fibrosis in individuals with a BMI ≥ 25 kg/m2. These findings indicate a function for leptin in promoting liver fibrosis; however, longitudinal studies are required to elucidate the causal nature of this interaction.