Human Serum Albumin (HSA) is a single polypeptide chain composed of 585 amino acids, with a molecular weight of ~66.5 kDa. It is rich in cysteine residues (17 disulfide bonds) and lacks carbohydrates, making it highly soluble and stable. The protein folds into a heart-shaped tertiary structure with three homologous domains (I, II, and III), each divided into two subdomains (A and B). The structure is stabilized by disulfide bonds and hydrophobic interactions. HSA has multiple ligand-binding sites, notably for fatty acids, hormones, and drugs, located in hydrophobic pockets and flexible loops. HAS is a vital multifunctional plasma protein critical for homeostasis. It maintains ~80% of plasma colloid osmotic pressure to prevent vascular fluid leakage, transports hydrophobic molecules (e.g., fatty acids, hormones, drugs) and metal ions (Ca²⁺, Cu²⁺), and exerts antioxidant activity via its Cys-34 thiol group to neutralize free radicals and bind pro-oxidant metals. HSA also buffers blood pH using histidine residues and supports endothelial stability by regulating vascular permeability and nitric oxide bioavailability, thereby modulating blood flow. These roles collectively highlight HSA’s indispensable contribution to systemic health and disease regulation. HSA exhibits significant evolutionary conservation, sharing high sequence homology with serum albumin in other mammals. For instance, it shows ~76% sequence identity with Bovine Serum Albumin (BSA) and ~78% identity with Mouse Serum Albumin, highlighting its structural and functional preservation across species. This homology extends to its three-domain architecture (domains I, II, and III) and the characteristic disulfide bond patterns, both of which are remarkably conserved. low levels, caused by reduced synthesis (e.g., liver cirrhosis), excessive loss (e.g., nephrotic syndrome), malnutrition, or inflammation (e.g., sepsis), leads to edema, ascites, impaired drug efficacy, and poorer outcomes in critical illnesses. Conversely, elevated levels, typically due to dehydration (hemoconcentration) or rare genetic factors, is often transient but may signal chronic inflammation or metabolic disorders if persistently elevated. Applications of the Human Serum Albumin Competitive OneStep ELISA Kit: Human Serum Albumin Competitive OneStep ELISA kit enables rapid, accurate quantification of Serum Albumin in serum, plasma, or cell culture supernatants. Advantages of this Competitive OneStep ELISA Kit Design: Simplified Workflow: Combines sample incubation and detection in a single step, eliminating intermediate washing and reducing hands-on time. High Efficiency: Achieves results within 1 hours, ideal for high-throughput studies or urgent diagnostics. Enhanced Precision: Minimizes procedural variability and cross-contamination risks through optimized reagent formulation. Broad Compatibility: Validated for diverse biological matrices, ensuring flexibility in experimental design. This kit’s streamlined protocol and robust performance make it an indispensable tool for researchers and clinicians seeking reliable Serum Albumin quantification in time-sensitive or resource-limited settings.