Albumin

The reference range for albumin testing is as follows: ^{[1, 2]}

• The normal range is 3.5 to 5.5 g/dL or 35-55 g/liter. This range may vary slightly in different laboratories.

• Albumin composes 50%-60% of blood plasma proteins.

An image depicting human serum albumin can be seen below.

The albumin test measures the amount of albumin in the clear liquid portion of blood.

Dehydration is associated with "high" levels of albumin.

Conditions associated with "low" levels of albumin are as follows:

• Ascites

• Burns

• Glomerulonephritis ^[3]

• Liver disease (hepatitis or cirrhosis)

• Malabsorption syndromes (eg, Crohn disease, celiac disease, or Whipple disease)

• Malnutrition

Other states are as follows:

• Nephropathy

• Hepatic encephalopathy

• Hepatorenal syndrome

• Sprue

• Wilson disease

Methods

Details are as follows:

• Specimen type: Blood

• Container: Vacuum tubes

• Collection method: Venipuncture

• Albumin tester: A digital sensing platform running on a smart phone. ^[4]

Panels

Albumin testing is part of a comprehensive metabolic panel. The liver panel is a related test.

Description

Albumin is a blood plasma protein synthesized in the liver. It is the single most abundant protein in plasma and constitutes about two-thirds of total protein content. Because it is the main protein in human blood, decreases in albumin due to decreased synthesis or losses result in impaired regulation of intravascular oncotic pressure and manifests as edema. As such, it transports certain hormones (eg, thyroid, estrogen, cortisol) when their specific binding globulins are saturated, as well as unconjugated bilirubin and other organic anions and many drugs (eg, penicillin, warfarin). Albumin is soluble in water, precipitated by acid, and coagulated by heat. The chief functions of albumin are to transport a wide variety of ligands, to maintain plasma oncotic pressure, and to serve as a source for endogenous amino acids. ^{[1, 2]}

Several methods exist for determining albumin levels, including dye-binding methods, electrophoresis, and immunochemical methods, as well as dipstick methods for urinary albumin.

For the determination of albumin in serum/plasma, the patient should stop taking drugs that affect albumin measurements, such as anabolic steroids, androgens, growth hormones, ^[5] and insulin.

A blood sample is put in a centrifuge, which spins and separates the cells from the serum.

Indications/applications

The albumin test helps to determine if the patient has liver or kidney disease or if the body is not absorbing enough protein.

Indications for the albumin test are as follows:

• Jaundice ^[6]

• Fatigue

• Weight loss

• Symptoms of nephrotic syndrome (swelling around eyes, belly, or legs)

Causes of changes in albumin levels are as follows:

• Decreased production (low protein diet or malnutrition, malabsorption)

• Cirrhosis of the liver

• Excess excretion by the kidneys (ascites or protein-losing nephropathy or enteropathy) ^[7]

• Prolonged diarrhea

• Loss from skin through burns

A study by Kawaguchi et al indicated that in patients with nonalcoholic fatty liver disease (NAFLD), reductions in serum albumin are predictive of serious complications. While in study patients without serious complications, the serum albumin level declined by 0.04 g/dL/year, in, for example, those who suffered hepatic failure, the level was reduced by 0.38 g/dL/year, and in patients with gastroesophageal varices, by 0.25 g/dL/year. ^[8]

Limitations

See the list below:

• Albumin production is decreased during pregnancy.

• Patients taking large amounts of intravenous fluids may have inaccurate results.

• The test may need to be performed with creatinine and blood urea nitrogen tests to evaluate kidney function. ^[9]

• This test may need to be performed with a prealbumin test to evaluate nutritional status.

• Marked lipemia can interfere with albumin measurement.