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Total Protein and A/G Ratio
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The Test
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How is it used?When is it ordered?What does the test result mean?Is there anything else I should know?
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.
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?NOTE: A standard reference range is not available for this test. Because
reference values are
dependent on many factors, including patient age, gender, sample population, and test
method, numeric test results have different meanings in different labs. Your lab report
should include the specific reference range for your test. Lab Tests Online strongly
recommends that you discuss your test results with your doctor. For more information on
reference ranges, please read Reference Ranges
and What They 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. |
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This article was last reviewed on
August 10, 2005.
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