Correlation Between Fibroblast Growth Factor 21 And Non-Alcoholic Fatty Liver Disease in Hypothyroid Patients

Background: Thyroid dysfunction, particularly hypothyroidism, is increasingly recognized as a contributor to metabolic dysregulation and non-alcoholic fatty liver disease (NAFLD). Fibroblast growth factor-21 (FGF21) has emerged as a metabolic stress hepatokine, while the Fibrosis-4 (FIB-4) index is a widely used noninvasive fibrosis marker. We aimed in this research to evaluate the relationship between serum FGF21 levels, FIB-4 scores, and the presence and severity of NAFLD in patients with hypothyroidism.Methods: A prospective case–control study including 39 hypothyroid patients with ultrasonographic NAFLD and 39 healthy controls. Clinical assessment, anthropometry, biochemical testing, thyroid profiles, lipid parameters, and FGF21 measurement by enzyme-linked immunosorbent assay (ELISA) were performed. NAFLD severity and fibrosis risk were assessed using FIB-4. Results: Cases demonstrated significantly higher body mass index (BMI), central adiposity indices, systolic,diastolic blood pressure, triglycerides, total cholesterol, low-density lipoprotein (LDL), glycated hemoglobin (HbA1c), aspartate aminotransferase (AST), FGF21, FIB-4 than controls, along with significantly lower high-density lipoprotein (HDL) platelet counts (all p < 0.0001). Receiver operating characteristic (ROC) analysis confirmed their strong diagnostic value for (NAFLD, with FGF21 demonstrating an area under the curve (AUC) of 1.000, sensitivity 100%, and specificity 98.4% (p < 0.0001), while FIB-4 showed an AUC of 0.996, sensitivity 100%, specificity 93.7% (p < 0.0001).Conclusion: Hypothyroid patients with NAFLD display marked metabolic and hepatic abnormalities. Elevated FGF21 and FIB-4 reliably indicate higher fibrosis risk, with FGF21 reflecting metabolic stress and FIB-4 offering stronger specificity for structural liver injury. Together, these markers enhance early detection and risk stratification of NAFLD in hypothyroid patients