Total Protein and A/G Ratio Tests

At a Glance

Also known as

TP, Albumin/Globulin ratio

Formal Name

Total Protein; Albumin/Globulin ratio

Related tests

Albumin, Liver panel, Protein Electrophoresis

Why get tested?

To determine your nutritional status or to screen for certain liver and kidney disorders as well as other diseases

When to get tested?

If you experience unexpected weight loss or fatigue or if your doctor thinks that you have symptoms of a liver or kidney disorder

Sample required

A blood sample drawn from a vein in your arm of by fingerstick (adults and children) or heelstick (newborns)

The Test Sample

What is being tested?

The total protein test is a rough measure of all of the proteins in the plasma portion of your blood. Proteins are important building blocks of all cells and tissues; they are important for body growth and health. Total protein measures the combined amount of two classes of proteins, albumin and globulin. Albumin is a carrier of many small molecules, but its main purpose is to keep fluid from leaking out of blood vessels, while globulin proteins include enzymes , antibodies , and more than 500 other proteins. The ratio of albumin to globulin (A/G ratio) is calculated from values obtained by direct measurement of total protein and albumin. It represents the relative amounts of albumin and globulins.

How is the sample collected for testing?

A blood sample is obtained by inserting a needle into a vein in your arm or by a fingerstick (for children and adults) or heelstick (for newborns).

The Test

How is it used?

Total protein measurements can reflect nutritional status, kidney disease, liver disease, and many other conditions. If total protein is abnormal, further tests must be performed to identify which protein fraction is abnormal, so that a specific diagnosis can be made.

When is it ordered?

Total protein is ordered to provide general information about your nutritional status, such as when you have undergone a recent weight loss. It is also ordered along with several other tests to provide information if you have symptoms that suggest a liver or kidney disorder, or to investigate the cause of abnormal pooling of fluid in tissue (edema).

What does the test result mean?

Low total protein levels can suggest a liver disorder, a kidney disorder, or a disorder in which protein is not digested or absorbed properly. Some laboratories also report the calculated ratio of albumin to globulins, termed the A/G ratio. Normally, there is a little more albumin than globulins, giving a normal A/G ratio of slightly over 1. Because disease states affect the relative changes in albumin and globulins in different ways, this may provide a clue to the physician as to the cause of the change in protein levels. A low A/G ratio may reflect overproduction of globulins (such as seen in multiple myeloma or autoimmune diseases) or underproduction of albumin (such as occurs with cirrhosis) or selective loss of albumin from the circulation (as occurs with nephrotic syndrome). A high A/G ratio suggests underproduction of immunoglobulins (as may be seen in some genetic deficiencies and in some leukemias). More specific tests, such as albumin, liver enzyme tests, and serum protein electrophoresis must be performed to make an accurate diagnosis.

Is there anything else I should know?

Prolonged application of a tourniquet during blood collection can result in a blood sample that has a higher protein concentration than the rest of the circulation. This will mean that the test result for total protein will be falsely elevated (higher than the actual concentration in the circulation). Drugs that may decrease protein levels include estrogens and oral contraceptives.

Common Questions

1. Can I test for protein levels at home?

   No, there is no home test available.

2. Will a high protein diet raise my total protein?

   No, increasing your intake of protein will not increase your total protein test result.

3. What type of nutrition is recommended for optimal protein levels?

   A well-balanced diet that follows the recommendations of the United States Department of Agriculture and is summarized by the Food Pyramid.