Albumin is the most abundant protein in the bloodstream and serves several vital functions: it carries hormones, drugs and fatty acids through the blood; it maintains oncotic pressure (which keeps fluid inside blood vessels rather than leaking into tissues); and its level is a broad indicator of nutritional and liver health.
Normal range and what low albumin indicates
A normal albumin level is typically 35–50 g/L. Levels below 35 g/L are considered hypoalbuminaemia. The lower the level, the more clinically significant the finding. Low albumin can result from inadequate dietary protein, impaired production in the liver, losses through damaged kidneys or inflamed gut, or from the acute-phase response where the body diverts resources away from albumin synthesis during illness.
Chronically low albumin is associated with poorer surgical outcomes, longer hospital stays and higher mortality in critically ill patients — not because albumin itself causes harm, but because it reflects the severity of underlying illness.
Causes of low albumin
- Liver disease — cirrhosis significantly impairs albumin production
- Nephrotic syndrome — kidneys leak large amounts of albumin into urine
- Inflammatory bowel disease — protein is lost through the inflamed gut wall
- Malnutrition or malabsorption — insufficient protein intake
- Acute illness or surgery — inflammatory response suppresses albumin synthesis
- Burns — massive protein losses through damaged skin
What happens next
Treatment depends on the cause. Nutritional albumin deficiency is addressed with dietary protein and, where needed, supplemental nutrition. Organ-related causes — liver disease, nephrotic syndrome — require treatment of the underlying condition. In acute settings, albumin infusions are sometimes used, though the evidence for routine replacement is limited and context-specific.