Plasma protein tests are blood tests that detect the amount of proteins in the blood. Such lab work is often ordered as part of a comprehensive metabolic panel (CMP) during a physical exam. This screening tool can help a doctor determine your overall health.
Also called total protein or albumin tests, plasma protein tests may also be ordered if your doctor suspects that you have certain underlying health conditions, such as inflammation or certain autoimmune conditions (rheumatoid arthritis, celiac disease, etc.). Depending on your condition, your physician may order follow-up blood work as part of your treatment plan.
Doctors order plasma protein tests in order to measure the amounts of specific proteins in the blood. Total protein levels may be higher or lower than average in the case of certain health disorders. These include:
- bone marrow disorders
- edema (a buildup of fluid in the tissues)
- hepatitis (liver infection)
- inflammatory bowel diseases
- kidney disease
- liver disease
Plasma protein test results often coincide with your overall CMP results. Abnormal protein counts can indicate potential health problems. Higher than normal protein levels are associated with:
- bone marrow disorders
On the other hand, a low plasma protein level may be a sign of:
- severe malabsorption of nutrients and subsequent malnutrition
- kidney or liver disease
- bowel problems
In addition to albumin levels, your protein test may also detect blood levels of globulin. This is called an A/G ratio. According to the American Association for Clinical Chemistry (AACC), a normal A/G ratio is just above 1, with albumin being higher than globulin (Lab Tests Online, 2013).
If this ratio is off, it can affect your total protein count. Low A/G ratios are associated with too much globulin, which can cause autoimmune diseases. High A/G ratios can indicate leukemia or bowel disorders.
Once your doctor gives you an order for a total protein test, you should have it done immediately. Some offices provide in-house blood work. This means you may be able to have your blood drawn during your appointment. In many cases, you will have to travel to a lab to get your blood drawn. Make sure that the lab you go to is covered by your insurance.
Your physician may request that you fast, or not eat food and drink, for several hours before the plasma protein test. Make sure to tell your doctor about any medicines you currently take, as they may interfere with the results. For example, birth control pills and estrogen medicines may decrease blood protein levels.
Like other types of blood work, plasma protein tests carry few risks. If you are sensitive to needles, you may experience slight pain or discomfort. While the process normally takes just a few minutes, it might take longer in patients with smaller veins. You may experience bruising at the puncture site, as well as temporary dizziness. Call your doctor if you have signs of infection, such as redness, inflammation, and discharge, after the procedure.
Medical professionals must be mindful of the use of tourniquets during the blood drawing process. According to the AACC, these arm compressing devices can produce false results when kept on for too long. With a tourniquet, your total protein levels may be measured as higher than they really are.
Normal results do not require any follow-up tests, unless your doctor detects other concerns with your CMP. The situation is different if your total protein test results are abnormal. In this case, your doctor will likely order a series of follow-up tests, such as:
- C-reactive protein tests to detect heart disease
- immunoglobulin A (IgA) tests to measure antibodies and help diagnose autoimmune diseases
- liver enzyme tests to detect related diseases and inflammation
- protein electrophoresis to monitor blood protein loss