What it measures.
Albumin is the most abundant protein in blood, produced by the liver. It maintains fluid balance, transports hormones and drugs, and serves as a marker of nutritional status and liver function. Low albumin is strongly associated with increased mortality and accelerated biological aging.
The concentration of albumin protein in blood. Albumin comprises about 50% of plasma protein and has a half-life of 15-20 days.
Why it matters.
Albumin is a powerful predictor of mortality across populations. Levels below 3.5 g/dL are associated with significantly increased risk of death, hospitalization, and poor outcomes from illness or surgery. It reflects both nutritional status and chronic disease burden.
Physiology.
The liver synthesizes albumin at about 10g/day in healthy adults. Albumin maintains oncotic pressure (keeping fluid in blood vessels), transports fatty acids, hormones, and drugs, and serves as an antioxidant. Production decreases with malnutrition, liver disease, and inflammation.
Testing & preparation.
How to prepare
- No special preparation needed
- Often part of comprehensive metabolic panel
- Dehydration can falsely elevate results
When to test
Part of routine health screening, evaluating nutritional status, liver function assessment, or biological age panel.
How often
Annually as part of comprehensive metabolic panel.
Interpretation.
High albumin
Common causes:
- Dehydration (concentrated blood)
- Rarely clinically significant
Implications:
- Usually reflects fluid status rather than excess production
Low albumin
Common causes:
- Malnutrition or inadequate protein intake
- Liver disease (reduced synthesis)
- Chronic inflammation (negative acute phase reactant)
- Kidney disease (nephrotic syndrome—urinary loss)
- Protein-losing enteropathy
- Burns, severe wounds (loss and consumption)
Implications:
- Increased mortality risk
- Poor wound healing
- Edema (fluid leaking from vessels)
- Reduced drug transport and effectiveness
- Marker of catabolic state
- Associated with frailty in elderly
Optimization.
Diet
- Adequate protein intake (1.0-1.2 g/kg bodyweight minimum)
- High-quality protein sources (eggs, fish, meat, dairy)
- Adequate overall caloric intake
Lifestyle
- Address underlying chronic conditions
- Regular physical activity (preserves muscle and protein status)
- Adequate sleep for recovery and synthesis
Supplements
- Protein supplementation if dietary intake insufficient
- Address inflammation if contributing to low albumin
FAQs.
Why is albumin used in biological age calculations?
Multiple large studies show that serum albumin strongly predicts mortality, independent of age. The UK Biobank analysis of 300,000+ participants found albumin among the best mortality predictors. Low albumin reflects multiple age-related processes: reduced liver synthetic capacity, chronic inflammation, malnutrition, and catabolic metabolism. It captures overall physiological 'wear and tear' that accelerates biological aging.
How can I increase low albumin?
Address the underlying cause first. If nutritional: increase protein intake to 1.2-1.5 g/kg bodyweight with high-quality sources. If inflammatory: treat the underlying condition and reduce inflammation. If liver disease: manage the condition with appropriate medical care. General strategies include adequate sleep, regular exercise (preserves muscle protein), and addressing any chronic illness. Improvement takes weeks as albumin has a 15-20 day half-life.