What Is Serum Albumin?
Albumin is the most abundant protein in the blood, made exclusively by the liver. It maintains fluid balance by keeping water in the blood vessels, transports hormones, drugs and nutrients, and reflects nutritional status and liver synthetic function.
Normal Albumin Range
| Result | Albumin (g/dL) | Interpretation |
|---|---|---|
| Normal | 3.5–5.0 | Adequate nutrition and liver function |
| Mildly low | 3.0–3.5 | Mild hypoalbuminaemia — monitor |
| Moderately low | 2.5–3.0 | Significant concern — investigate |
| Severely low | Below 2.5 | Severe hypoalbuminaemia — risk of oedema, infection |
Causes of Low Albumin
| Category | Causes |
|---|---|
| Liver disease | Cirrhosis, hepatitis — impaired albumin synthesis |
| Kidney disease | Nephrotic syndrome — albumin leaks into urine |
| Malnutrition | Inadequate protein intake, malabsorption |
| Inflammation/infection | Acute-phase response — liver shifts priority away from albumin |
| Burns | Massive protein loss through damaged skin |
| Protein-losing enteropathy | Albumin lost through diseased bowel |
Consequences of Low Albumin
- Oedema — fluid leaks from blood vessels into tissues (swollen ankles, ascites)
- Altered drug binding — affects dosing of highly protein-bound medications
- Impaired wound healing
- Higher infection risk
- Marker of poor prognosis in critical illness and cancer
Albumin as a Nutritional Marker
Albumin has a 20-day half-life — it reflects nutritional status over weeks, not days. Pre-albumin (transthyretin) with a 2-day half-life is better for monitoring acute nutritional changes.
FAQs
Can albumin be low with normal liver enzymes (ALT/AST)?
Yes — in cirrhosis, liver enzymes may normalise but albumin falls as liver function declines. Low albumin with prolonged PT is a sign of decompensated liver disease.
Does dehydration affect albumin?
Yes — dehydration can artificially elevate albumin by concentrating blood. Overhydration lowers it.
Is fasting required?
No fasting needed for albumin.
Medical Disclaimer: Low albumin should always be investigated for its underlying cause by your doctor rather than treated with albumin infusions alone.