Albumin (ALB) Blood Test

Albumin is a protein made by the liver that helps carry substances in the blood and keeps fluid inside blood vessels. This blood test, often part of a metabolic or liver panel, can show how well the liver and kidneys are working and whether nutrition is adequate.

Albumin is the most abundant protein in blood plasma, made almost entirely by the liver. Once released into circulation, it helps keep fluid inside blood vessels by creating oncotic pressure, which prevents fluid from leaking into surrounding tissues. Albumin also acts as a carrier, binding to and transporting hormones, vitamins, fatty acids, certain medications, and minerals such as calcium throughout the body. Because the liver must be functioning well to produce enough albumin, and the kidneys must filter blood properly to keep it from leaking into urine, albumin levels can reflect the health of both organs as well as overall nutrition status.

A healthcare provider may order an albumin test as part of a comprehensive metabolic panel or a liver panel to check how the liver and kidneys are working. Low albumin can be a clue to liver disease, kidney problems, malnutrition, or long-term inflammation, while unusually high readings are often linked to dehydration rather than a disease process. Albumin is also checked alongside total protein to calculate the albumin-to-globulin ratio, which can offer more detail about certain chronic conditions. Because albumin binds calcium, providers may also review calcium results together with albumin.

Albumin results are usually reported in grams per deciliter (g/dL), and some labs use grams per liter (g/L) instead. Reference ranges for adults can vary somewhat between laboratories depending on the testing method used, so the exact numbers on a lab report may differ slightly from another lab's range. Always compare results to the range printed on the specific report.

A high albumin result is less common than a low one and is usually not caused by a disease of the albumin-producing process itself. The most frequent reason is dehydration: when the fluid part of the blood decreases, proteins like albumin appear more concentrated even though the total amount in the body has not changed. This can happen with low fluid intake, vomiting, diarrhea, or heavy sweating.

A high-protein diet or certain supplements may also raise levels modestly in some people. In hospital or clinic settings, a high reading can sometimes occur if a blood draw took a long time or a tourniquet was left on too long, since this can concentrate proteins in the sample—a lab artifact rather than a true health change.

Less often, high albumin has been associated with conditions that affect blood volume regulation. Because an elevated result is often tied to hydration status rather than illness, a healthcare provider will typically look at the whole clinical picture, including symptoms and other lab values like total protein, before drawing conclusions. Repeating the test after rehydration is a common next step.

Low albumin is a more common finding and can have several causes. Liver conditions that reduce the liver's ability to make protein—such as cirrhosis or hepatitis—can lower albumin over time, often alongside changes in ALT, AST, or total bilirubin. Kidney conditions that let protein leak into the urine, including nephrotic syndrome, are another well-known cause.

Poor nutrition, malabsorption disorders, and chronic illness can reduce the protein available to make albumin. Inflammation and infection can also lower albumin temporarily, since the liver shifts toward making other proteins during an immune response. Pregnancy and overhydration can dilute albumin as well. Because low albumin can reflect many different processes, a healthcare provider usually considers it together with symptoms, other lab results, and a person's overall health history.

Albumin is often interpreted alongside other liver panel markers such as ALT, AST, and total bilirubin, which together give a broader picture of liver health. Total protein is measured in the same panel and used to calculate the albumin-to-globulin ratio. Because albumin binds calcium in the blood, calcium results are sometimes adjusted based on albumin levels.

Hydration status, recent diet, pregnancy, and certain medications can all shift albumin readings without necessarily indicating disease. Reference ranges can vary from lab to lab depending on the testing method used, which is why results are best compared against the range listed on the specific lab report rather than a general number found online.

If an albumin result falls outside the reference range, it is best discussed with a healthcare provider, who can consider it alongside symptoms, medical history, and other lab values such as total protein and liver enzymes. Very low albumin can sometimes be linked to swelling, fatigue, or fluid buildup, and these symptoms are worth mentioning at any follow-up visit.

If you experience sudden swelling, difficulty breathing, or other severe symptoms, seek urgent medical care rather than waiting for routine follow-up.

Uploading a lab report to MediWing can help translate these numbers into plain language and track changes over time.