Used to measure fibroblast growth factor 21 (FGF-21) levels in mouse biological samples such as serum, plasma, or cell culture supernatants. It is widely applied in metabolic disease research, including studies on diabetes, obesity, and insulin resistance, where FGF-21 plays a regulatory role. The kit enables accurate quantification of FGF-21, supporting investigation into energy metabolism, liver function, and therapeutic responses in preclinical animal models. Its high sensitivity and specificity make it suitable for detecting low concentrations of FGF-21 in small sample volumes.