What the albumin test shows
Albumin is the most abundant protein in blood, and the test measures how much is circulating in serum. The liver makes it — about 10–15 grams a day — and releases it straight into the blood, so albumin is a key window on liver function. StatPearls notes it accounts for roughly half of all the protein in plasma.
Two jobs make it matter. Albumin holds fluid inside blood vessels by generating most of the blood’s oncotic (colloid osmotic) pressure; when it falls, fluid leaks into the tissues and causes swelling. It also acts as a transport truck for calcium, bilirubin, hormones, fatty acids and many medicines.
It differs from the markers ordered beside it. Total protein measures albumin plus all the globulins (antibodies and other proteins) together, so albumin is the largest single slice of that total. Liver enzymes such as ALT and AST flag damage to liver cells; albumin, with a long half-life of about three weeks, instead reflects the liver’s manufacturing capacity over weeks and changes slowly rather than spiking — a marker of longer-term status, not a sudden event.
Albumin normal range
Albumin is reported in conventional units (g/dL) and SI units (g/L); to convert, g/dL × 10 = g/L, so 4.0 g/dL equals 40 g/L. Rough adult orientation:
| Group | Conventional (g/dL) | SI (g/L) |
|---|---|---|
| Adults | ~3.5–5.0 | ~35–50 |
| Adults 70+ | ~3.2–4.6 | ~32–46 |
| Pregnancy (later) | ~3.0–4.0 | ~30–40 |
| Newborns / children | ~2.8–4.4 | ~28–44 |
Sex makes little difference — men run marginally higher — so most labs use one adult band. Levels drift down with age and fall in pregnancy from the extra fluid in the circulation; some labs set the upper limit as high as 5.4–5.5 g/dL. Because methods and populations differ, always read your result against the reference interval on your own report (MedlinePlus).
Why albumin is low
Low albumin (hypoalbuminemia) is common, and usually a sign of something else rather than a disease of albumin itself. By mechanism, roughly by frequency:
- Inflammation and acute illness (commonest). Albumin is a negative acute-phase protein: during infection, sepsis, surgery, trauma or a flare of chronic disease, the liver makes less of it, so albumin drops while CRP climbs. This is the leading reason for a low value, especially in hospital.
- Liver disease. Cirrhosis and other chronic liver damage cut the liver’s ability to make albumin, which is why it is read with ALT, AST and bilirubin when liver function is in question.
- Kidney loss (nephrotic syndrome). Damaged kidney filters leak albumin into the urine; the classic picture is low blood albumin, heavy protein in the urine, swelling and a raised total cholesterol.
- Poor intake or malabsorption. Protein–energy malnutrition, celiac disease, inflammatory bowel disease and protein-losing gut conditions lower it over time.
- Dilution and third-space loss. Heart failure, cirrhosis with ascites, large volumes of IV fluid, extensive burns and pregnancy all spread albumin thinner or lose it from the circulation.
Often two or more act together, as StatPearls notes; the visible sign of a genuinely low albumin is swelling of the ankles, around the eyes, or in the abdomen.
When is it urgent? A very low albumin (below about 2.0–2.5 g/dL) or a rapid fall during acute illness tends to travel with serious disease — it is a well-established predictor of worse outcomes in hospital and critical care — and warrants prompt assessment, as does new marked swelling or breathlessness.
Why albumin is high
High albumin (hyperalbuminemia) is far less common and is almost never a disease of albumin itself:
- Dehydration (by far the commonest). With less water in the blood, everything left behind — albumin included — reads more concentrated. It is a relative rise, not a true excess, and corrects with rehydration; severe vomiting or diarrhea can do the same.
- Blood-draw artifact. A tourniquet left on too long (venous stasis) concentrates proteins in the sample and can nudge albumin up spuriously.
No common condition makes the body overproduce albumin, so a high value rarely signals hidden disease on its own — check hydration and repeat if needed (Cleveland Clinic). Because dehydration concentrates other markers too, a high albumin often appears with a raised hemoglobin and urea on the same sample.
What to test alongside
Albumin is read as part of a panel, not alone:
- Total protein — albumin plus globulins; the albumin-to-globulin (A/G) ratio comes from the two.
- ALT, AST, bilirubin, GGT and alkaline phosphatase — the rest of the liver panel; albumin is its synthetic member.
- Creatinine and urea — kidney function, central when nephrotic syndrome is suspected.
- CRP — inflammation, the commonest reason albumin runs low.
- Total cholesterol and LDL cholesterol — both rise in nephrotic syndrome as albumin falls.
- Ferritin — a companion in chronic illness; it climbs with inflammation while albumin drops.
What to do about an abnormal result
- Don’t self-treat. Protein powders or supplements will not fix a low albumin caused by inflammation, liver or kidney disease, and can distract from the real problem.
- Repeat in context. Albumin dips with almost any acute illness, so an isolated low value is usually rechecked once you are well, paired with CRP.
- For a low albumin, your primary-care doctor works through the causes — liver (ALT, AST, bilirubin), kidney (urine protein plus creatinine) and nutrition — and treats the condition, not the number.
- For a high albumin, rehydrate and repeat; a value that stays high on a well-hydrated sample is unusual and worth review.
- See your GP or primary-care physician first. They coordinate the next test and refer to hepatology (liver), nephrology (kidney) or gastroenterology (gut) as needed.
Mini-FAQ
What does a low albumin level mean?
Most often inflammation or acute illness — albumin falls when you are unwell — or liver disease, kidney loss through nephrotic syndrome, or poor nutrition. It is read alongside CRP and liver and kidney tests to find the cause.
What is a normal albumin level?
Roughly 3.5–5.0 g/dL (35–50 g/L) in healthy adults, a little lower in older age and in pregnancy. Each lab prints its own reference range, so read your result against that.
Does a high albumin mean something is wrong?
High albumin is almost always dehydration, or a tourniquet left on too long during the blood draw, rather than a disease of albumin itself. It usually corrects once you are properly hydrated.
Can low albumin be fixed by eating more protein?
Only when poor intake is the actual cause. Most low albumin comes from inflammation, liver or kidney disease, so treating the underlying problem matters far more than diet alone.
Which doctor should I see for an abnormal albumin?
Start with your primary-care doctor, who repeats the test in context and checks liver, kidney and inflammation markers. They refer you to a liver, kidney or gut specialist if the results point that way.
