Albumin (ALB) is a major serum protein with multifaceted physiological functions centered on transport and metabolic regulation. Structurally, ALB binds water, calcium, sodium, potassium, fatty acids, hormones, bilirubin, and drugs, with its primary function being regulation of blood colloidal osmotic pressure [UniProt]. As the major zinc transporter in plasma, ALB typically binds approximately 80% of circulating plasma zinc, with a binding affinity hierarchy of zinc > calcium > magnesium, and a potential shared binding site at Asp-273 suggesting zinc-calcium transport crosstalk [19021548]. ALB also binds approximately 45% of circulating calcium and magnesium in plasma [UniProt]. Notably, ALB binds bacterial siderophore enterobactin and inhibits enterobactin-mediated iron uptake by E. coli from ferric transferrin, thereby limiting enteric bacterial iron utilization and growth, though it does not prevent aerobactin-mediated iron uptake [6234017]. Beyond transport functions, ALB demonstrates antioxidant activity and bilirubin transport capacity [GO annotations]. Clinically, ALB levels serve as an important biomarker; elevated systemic immune-inflammation index/albumin ratios independently predict worse overall and recurrence-free survival in hepatocellular carcinoma patients undergoing curative resection [39735268]. Additionally, PCT/ALB and CRP/ALB ratios correlate with severity and prognosis in craniocerebral trauma [39165205]. Genetic variants of ALB, including inherited bisalbuminemia, show geographic variation in prevalence [34919010].