What Is Albumin in a Blood Test?

Albumin is the most abundant blood protein, produced exclusively by the liver. It maintains fluid inside blood vessels and transports hormones, drugs, and fatty acids.

Normal Range

• 3.5–5.0 g/dL
• Low: below 3.5 g/dL
• Severe: below 2.5 g/dL — edema and poor prognosis

Low Albumin Causes

• Liver disease — cirrhosis, hepatitis
• Kidney disease — nephrotic syndrome
• Malnutrition
• Inflammation — albumin is a negative acute-phase reactant
• Malabsorption
• Burns
• Protein-losing enteropathy

High Albumin Causes

• Dehydration — hemoconcentration (relative increase only)

Clinical Significance

• Key marker of liver synthetic function
• Low albumin + elevated bilirubin + prolonged PT = advanced liver disease
• Affects total calcium accuracy — use corrected calcium when albumin is low