Albumin

Overview

Albumin is the most abundant protein in blood plasma, primarily produced by the liver, and it measures nutritional status, liver synthetic function, and vascular permeability. It maintains oncotic pressure to prevent fluid leakage from blood vessels and transports hormones, drugs, and fatty acids. Low levels (hypoalbuminemia) often indicate chronic liver disease, malnutrition, kidney disorders like nephrotic syndrome, or inflammation, while high levels are less common and may reflect dehydration. Clinically, albumin is useful for assessing prognosis in critical illness, guiding fluid therapy, and monitoring chronic disease progression.​

Clinical Use Cases

  • Evaluating liver function in cirrhosis or hepatitis.
  • Assessing nutritional status in malnutrition or critical illness.
  • Diagnosing and monitoring kidney disease, such as nephrotic syndrome.
  • Predicting outcomes in sepsis, surgery, or ICU patients.
  • Adjusting fluid management in dehydration or edema.

Specimen Types

  • Serum (most common).
  • Plasma.
  • Urine (for microalbumin in early kidney damage).

Measurement Methods

  • Colorimetric assays (e.g., bromocresol green or purple dye-binding).
  • Immunoassays (e.g., nephelometry or turbidimetry).
  • Capillary electrophoresis.
  • High-performance liquid chromatography (HPLC).

Test Preparation and Influencing Factors

  • No fasting required for serum albumin.
  • Posture: Levels may decrease after assuming upright position due to fluid shifts.
  • Inflammation or acute illness: Lowers levels as negative acute-phase reactant.
  • Dehydration: Falsely elevates levels.
  • Nephrotic syndrome or protein-losing enteropathy: Lowers levels via urinary or GI loss.

Synonyms

  • Serum albumin.
  • Human serum albumin (HSA).
  • Fraction V albumin.

Further Reading

  • Albumin Blood Test. MedlinePlus (National Library of Medicine).