Total protein blood test: albumin, globulin and what changes them

Blood plasma carries many proteins. Albumin, made only in the liver, is the most plentiful and holds fluid in blood vessels and carries substances. Globulins are a mixed group that includes antibodies, transport proteins and clotting-related proteins. Lab Tests Online UK defines total protein as albumin plus all other proteins in blood, including antibodies made to fight infection, and its formal name pairs it with the albumin to globulin ratio.

Because total protein is the sum, a change in one component can be offset by an opposite change in another. That is why the result is mainly useful as a screen: the clinician follows an abnormality with albumin and other tests that tell which protein has moved.

The test mostly forms part of a liver function test profile and is rarely required alone. Lab Tests Online UK says it can be used to calculate globulin, which may indicate activation or depletion of the immune system, and can help indicate certain liver and kidney disorders and several other diseases.

In liver profiles, total protein is usually normal in liver disease. The difference between total protein and albumin, the globulin, tends to increase when albumin falls, and very high values are seen most commonly in alcoholic hepatitis and in autoimmune hepatitis, according to the same source.

No preparation is needed. Blood is taken from a vein. Prolonged application of a tourniquet during blood collection can raise total protein, so a smooth collection matters. Anabolic steroids, androgens, growth hormone, insulin and progesterone may increase protein levels, whereas oestrogens may decrease them. There is no home test, and one would be of little value without other tests.

Low total protein can suggest a liver disorder, a kidney disorder, a disorder in which protein is not digested or absorbed properly, or immunoglobulin not being made, for example in bone marrow failure. Lab Tests Online UK stresses that more specific tests, such as albumin and liver enzyme blood tests, must be performed to make an accurate diagnosis.

In its liver tests guide the same source explains that low albumin can reflect extensive loss of liver tissue in long-standing disease, malnutrition, kidney disease with protein loss in urine, and inflammatory conditions anywhere in the body.

High levels can indicate dehydration, or some cancers that lead to accumulation of an abnormal protein such as immunoglobulin in multiple myeloma. A persistently high globulin fraction prompts tests such as protein electrophoresis to see whether a single abnormal band is present.

In many cases a mildly high value reflects dehydration or chronic inflammation and settles after rehydration or treatment of the cause.

Typical next tests are albumin, liver enzymes, kidney function, urine protein tests and, for high globulin, protein electrophoresis and immunoglobulin levels. The clinician interprets them with your symptoms, medicines and history. Seek prompt advice for swelling of the legs or abdomen, yellowing of the skin, or unexplained weight loss and bone pain.