The serum amyloid A4 (SAA4) antibody is a tool used to detect SAA4. a constitutively expressed member of the serum amyloid A (SAA) protein family. Unlike the acute-phase SAAs (SAA1 and SAA2), which are markedly upregulated during inflammation and linked to amyloidosis, SAA4 is produced at steady levels under normal conditions, primarily by the liver and certain epithelial cells. It is associated with high-density lipoproteins (HDL) and implicated in lipid metabolism, immune regulation, and cellular homeostasis. SAA4 shares structural homology with other SAAs but exhibits distinct functional roles, potentially influencing atherosclerosis, age-related diseases, or tissue repair. Antibodies targeting SAA4 enable researchers to study its expression patterns, tissue distribution, and pathological contributions. These antibodies are utilized in techniques like Western blotting, ELISA, and immunohistochemistry to explore SAA4’s role as a potential biomarker in chronic inflammatory conditions, metabolic disorders, or cancer. While its exact physiological significance remains less defined compared to acute-phase SAAs, SAA4’s conserved expression across species suggests fundamental biological importance, driving ongoing research into its mechanisms and therapeutic relevance.