Serum albumin is the most abundant plasma protein in human blood and is synthesised exclusively by the liver. It performs several essential physiological functions, including the maintenance of plasma oncotic pressure, transport of endogenous and exogenous substances, and regulation of intravascular fluid distribution. Albumin also serves as a carrier protein for numerous hormones, fatty acids, bilirubin, calcium, medications, and trace elements, making it fundamental to normal homeostasis.

Measurement of serum albumin forms part of routine biochemical testing and is widely used in primary care, emergency medicine, hospital practice, and critical care. Although albumin concentration is not a disease-specific marker, it provides valuable information regarding hepatic synthetic function, systemic inflammation, nutritional status, renal protein loss, and the severity of both acute and chronic illness.

Reduced serum albumin concentration, or hypoalbuminaemia, is a common laboratory finding with a broad differential diagnosis. Decreased albumin levels may result from impaired hepatic synthesis, increased renal or gastrointestinal protein loss, dilutional states, or increased catabolism during systemic inflammation. Common clinical causes include chronic liver disease, nephrotic syndrome, protein-losing enteropathy, severe infection, sepsis, burns, malignancy, major surgery, and chronic inflammatory disorders. While malnutrition may contribute to hypoalbuminaemia, low albumin should not be regarded as a specific marker of nutritional deficiency, particularly in the presence of acute illness or inflammation.

Persistent hypoalbuminaemia has been associated with increased morbidity, prolonged hospitalisation, delayed wound healing, and higher mortality across a wide range of medical and surgical conditions. Consequently, serum albumin is frequently incorporated into clinical risk assessment and prognostic evaluation.

Elevated serum albumin (hyperalbuminaemia) is uncommon and almost always reflects haemoconcentration resulting from dehydration or significant fluid loss rather than increased hepatic production. Correction of the underlying volume deficit typically restores albumin concentrations to the reference range.

Serum albumin is incorporated into several validated clinical equations and prognostic scoring systems. One of its most widely recognised applications is the calculation of corrected serum calcium, where albumin concentration is used to estimate calcium levels when alterations in protein binding affect total serum calcium measurements. Albumin also contributes to established liver disease scoring systems, nutritional assessment tools, and prognostic indices used across multiple clinical specialties.

Interpretation of serum albumin should always occur within the wider clinical context. Albumin concentration is influenced by numerous physiological and pathological processes, including hydration status, systemic inflammation, hepatic function, renal disease, gastrointestinal protein loss, and critical illness. Laboratory findings should therefore be considered alongside the patient’s history, physical examination, imaging, and other biochemical investigations.

Serum albumin remains an important biochemical marker in contemporary clinical practice. Its measurement supports diagnostic evaluation, disease severity assessment, prognostic stratification, interpretation of laboratory results, and application of validated clinical calculators. Appropriate interpretation of serum albumin concentrations contributes to accurate clinical decision-making and optimal patient management across a broad spectrum of healthcare settings.