Albumin is the main protein of the blood plasma, produced by the liver. It does two key jobs: it keeps fluid inside the vessels (creates oncotic pressure) and acts as transport — carrying hormones, fatty acids, calcium and drugs.
Albumin is an integral marker: it falls with liver disease, with protein loss through the kidneys, with undernutrition and with chronic inflammation. That is why it is included in biological-age models (PhenoAge) as an indicator of the body's overall "reserve".
Reference ranges
Reference for adults:
| Normal | 35 – 52 g/L |
| Mild reduction | 30 – 35 g/L |
| Marked hypoalbuminemia | below 30 g/L |
| Risk of edema | below 25 g/L |
What an elevated level means
A true rise in albumin is rare and usually has no independent clinical significance.
Almost always a "high" albumin is a consequence of dehydration: there is less fluid in the vessels, so the protein concentration is higher. This is an artifact, not a pathology. It can also be inflated by a prolonged tourniquet during the blood draw.
What a low level means
A fall in albumin is the most common and most significant finding. There are four groups of causes:
- Liver — does not produce enough (cirrhosis, severe hepatitis).
- Kidneys — lost in the urine (nephrotic syndrome).
- Nutrition — insufficient protein intake, malabsorption.
- Inflammation — with chronic inflammation and cancer, albumin falls as a negative acute-phase protein.
Clinically, low albumin leads to edema, and in biological-age models it is persistently associated with higher mortality — it is one of the strongest predictors in the PhenoAge formula.
How the test is done
Venous blood, usually as part of a biochemistry panel. Preferably fasting, in the morning.
Before testing, avoid dehydration — it inflates the result. Prolonged compression of the arm with a tourniquet also distorts the value. If albumin is low, the doctor will look for the cause: liver (ALT, AST, bilirubin), kidneys (protein in the urine), inflammation (CRP) or nutrition.
What affects the value
- Liver function — it is the only producer of albumin.
- Losses through the kidneys — in nephrotic syndrome.
- Dietary protein — insufficient intake lowers the level.
- Chronic inflammation — lowers albumin regardless of nutrition.
- Dehydration — falsely inflates the result.
- Age — over the years albumin naturally declines slightly.
Calculate using this marker
Calculators where Albumin is used directly:
Frequently asked questions
Low albumin — is it about the liver?
Not necessarily. There are four causes: liver (does not produce it), kidneys (lost in urine), nutrition (little protein) and chronic inflammation (lowers it as a negative acute-phase protein). To see which is yours, liver enzymes, urine protein and CRP are checked.
Can I raise albumin with a high-protein diet?
Only if the cause is specifically a protein shortfall in the diet. If albumin is low because of the liver, kidneys or inflammation, a protein diet will not solve the problem — the cause must be addressed.
Why is albumin part of the biological-age calculation?
Because it reflects several systems at once: the liver, kidneys, nutrition and inflammation level. That makes it a powerful integral marker of "reserve" — in the PhenoAge formula, low albumin is one of the strongest predictors of mortality.