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Albumin Blood Test

Albumin is the most abundant protein in your blood, made by the liver. Low albumin is a powerful indicator of liver disease, kidney disease, malnutrition or severe chronic illness.1

Written and clinically reviewed by Suman Konda, PharmD, Clinical Pharmacist · Based on peer-reviewed sources · Editorial policy · Not medical advice

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What is albumin?

Albumin is a protein produced exclusively by the liver and accounts for about 60% of total plasma protein. It performs several vital functions: maintaining oncotic pressure (keeping fluid inside blood vessels), transporting hormones, drugs, fatty acids, bilirubin and ions through the blood, and acting as an antioxidant and buffer. Albumin has a half-life of about 20 days, making it a useful marker of nutritional and liver status over weeks, not days. It is measured as part of a liver function test (LFT) panel and in kidney (nephrotic syndrome) workup.

Albumin normal range

CategoryRange (g/dL or g/L)Interpretation
Normal (adults)3.5 – 5.0 g/dL (35 – 50 g/L)Normal
Mildly low3.0 – 3.4 g/dLMild hypoalbuminaemia
Moderately low2.5 – 2.9 g/dLModerate
Severely low< 2.5 g/dLSevere: clinically significant

What does LOW albumin mean?

Low Albumin: Hypoalbuminaemia

Low albumin is called hypoalbuminaemia. It almost always indicates one or more of the following: (1) Liver disease (cirrhosis, hepatitis), the liver cannot make enough albumin; albumin is a sensitive indicator of liver synthetic function, and a falling albumin in liver disease indicates deterioration. (2) Nephrotic syndrome, the kidneys are losing protein into the urine, causing low blood albumin and oedema. (3) Malnutrition or malabsorption, insufficient amino acid intake or absorption to synthesise albumin. (4) Severe acute illness, sepsis or major burns, albumin moves out of the bloodstream into inflamed tissues (capillary leak) and production falls. (5) Protein-losing enteropathy, GI conditions (Crohn disease, lymphoma) causing protein loss through the gut.

Why does low albumin cause swelling?

Albumin is the main protein maintaining oncotic pressure (the force that keeps fluid inside blood vessels). When albumin falls below about 2.5 g/dL, oncotic pressure drops and fluid leaks from the bloodstream into surrounding tissues, causing oedema (swelling in the legs, ankles, abdomen and around the eyes). This is pitting oedema and is one of the key physical findings in hypoalbuminaemia from any cause.

High albumin: what it means

High albumin (hyperalbuminaemia) is almost always due to dehydration, which concentrates the blood. It is treated by ensuring adequate fluid intake.

Questions to ask your doctor

  • Is my low albumin from liver, kidney or nutritional causes?
  • Should I have a urine protein test to check for nephrotic syndrome?
  • Does this affect drug dosing (some drugs are albumin-bound)?
  • Am I getting adequate protein in my diet?
  • What is my liver's overall synthetic function?

Frequently asked questions

Why does my lab's Albumin range differ from the one shown here?
Every laboratory sets its own reference interval from the analyser, reagents and reference population it uses, so two labs can publish different Albumin intervals and both be correct, even reporting in the same g/dL. Read your result against the range printed on your own report.
Should a borderline Albumin result be repeated?
Usually. A value just outside the interval is common in people who are entirely well, since about one in twenty healthy results falls outside any 95% reference range by construction. A borderline Albumin is normally rechecked rather than acted on.
Does the trend matter more than one Albumin reading?
For long-term monitoring it generally does. A figure that has drifted across several tests says more than a single measurement, and a stable result sitting slightly outside the range is often simply that person's baseline.

References

The clinical information on this page is drawn from peer-reviewed sources indexed by the US National Library of Medicine. Links go to the source so you can read it yourself.

  1. Liver Function Tests. In: StatPearls. Treasure Island (FL): StatPearls Publishing. NCBI Bookshelf NBK482489

References

Sources cited on this page. PubMed links open the original abstract.

  1. Rothschild MA, Oratz M, Schreiber SS. Serum albumin. Hepatology. 1988;8(2):385–401. PMID 23877300 · doi:10.1002/hep.1840080234

Albumin as a nutritional and inflammation marker

Albumin is produced by the liver and is the most abundant protein in blood plasma. It serves several critical functions: maintaining oncotic pressure (keeping fluid inside blood vessels), transporting hormones, fatty acids, calcium, and drugs, and acting as a buffer. Because albumin has a half-life of 20 days, serum albumin reflects average protein synthesis and nutritional status over the preceding 3–4 weeks – unlike shorter-lived proteins such as prealbumin (half-life 2 days) which reflect more acute nutritional changes.

However, albumin is also a negative acute-phase reactant: during inflammation, infection, surgery, or trauma, the liver redirects amino acids toward producing acute-phase proteins (CRP, fibrinogen, ferritin) and decreases albumin synthesis. Additionally, inflammation increases vascular permeability, redistributing albumin out of the bloodstream. This means a low albumin in an acutely unwell patient may primarily reflect inflammation rather than malnutrition – always interpret albumin alongside CRP and other inflammatory markers.

Hypoalbuminaemia – the clinical consequences

When serum albumin falls below 30 g/L, the reduced oncotic pressure causes fluid to leak from the vascular compartment into the interstitium, producing oedema, ascites (fluid in the abdomen), and pleural effusions. This is particularly important in: nephrotic syndrome (albumin lost in the urine), liver cirrhosis (reduced synthesis), protein-losing enteropathy, and severe malnutrition. Low albumin also has practical consequences for drug dosing – many drugs (warfarin, phenytoin, calcium channel blockers) are heavily albumin-bound, and hypoalbuminaemia means a higher proportion of free (active) drug, increasing both effect and toxicity risk.

Adjusted calcium – why albumin changes the calcium result

Approximately 45% of serum calcium is bound to albumin. Standard total calcium measurements include both bound and free (ionised) calcium. When albumin is low, total calcium appears falsely low even though ionised (physiologically active) calcium may be normal. For every 1 g/L fall in albumin below 40 g/L, add 0.02 mmol/L to the total calcium to obtain the "corrected calcium." Most laboratories automatically report corrected calcium alongside total calcium to prevent this misinterpretation. Direct ionised calcium measurement (on arterial blood gas or specific analysers) avoids this adjustment and is preferred in critically ill patients where acid-base status also affects calcium binding.

Related reading

Medical Disclaimer: This page is for general educational purposes only and does not constitute medical advice. Always consult a qualified doctor for diagnosis and treatment decisions.
Content written and reviewed by Suman Konda, PharmD, Clinical Pharmacist · Telangana State Pharmacy Council · Sources linked to PubMed · Not medical advice – see our disclaimer