Total Protein Test: Why and How Is It Done?

Protein is one of the primary components of blood and forms an essential part of cells and tissues. Protein can be classified into two groups – albumin and globulin. Albumin prevents leakage of fluid from blood vessels, while globulin helps in boosting the immune system. These two classes of protein, along with the total composition of protein in the blood, can be accurately measured through a blood test called the Total Protein Test.

The test also evaluates the A/G ratio, that is, the ratio of albumin to globulin. Doctors usually prescribe this test as a part of medical treatment for health conditions of kidney and liver disease and diseases that cause fatigue and sudden weight loss.

Why Perform a Total Protein Test?

A Total Protein Test is often part of a routine health check-up. It is also one amongst the list of medical tests that are a part of the Comprehensive Medical Panel (CMP).

This medical test is recommended for diagnosing the following health conditions:

• Medical conditions of kidney and liver
• Illnesses that cause fatigue and sudden weight loss
• Edema, which is a type of inflammation due to the deposition of extra fluid in the tissues

Total Protein Test: Prerequisites

There are no preparations required before you undertake this TP blood test unless you are under certain medications like: 

• Androgens
• Steroids
• Dextran
• Corticosteroids
• Insulin
• Growth hormone
• Oestrogen
• Progesterone
• Ammonium ions
• Birth control pills
• Phenazopyridine

The above medications may affect the results of the total protein test. Inform your doctor in case you are taking any of the above medications. Tell them about any other vitamins, herbs, supplements, or drugs that you might be taking.

Your doctor will instruct you in case you need to avoid food or drinks before the TP test, or if you need to follow any other specifications. It is generally advised that you drink plenty of water before the test because dehydration can affect the accuracy of the results of the blood test.

Total Protein Test: Understanding the Results

The range of Total Protein that is considered normal is between 6 and 8.3 grams per decilitre (g/dL) but is subject to some variation at different labs where the Total Protein Test is undertaken.

The parameters that lead to the variations are age, gender, test procedure, and pregnancy. Low albumin is associated with malnutrition and liver diseases, and it can affect surgical patients because of delayed wound healing. High albumin is associated with infection, burn, stress from surgery or heart attack.

Low albumin levels also predict the recovery or effectiveness of treatments for ulcerative colitis. The lower albumin levels, the lower chances of recovery or successful treatment.

High Total Protein

Excessive protein content in the blood may be the symptom of chronic infection, medical condition of bone marrow like Waldentrom’s disease, or multiple myeloma. It may imply viral hepatitis, HIV/AIDS, and hepatitis B or C, which causes inflammation or infection.

Low Total Protein

Health conditions that adversely affect the smooth absorption of protein as in the case of digestive disorders such as celiac disease, or disorders of the liver or kidney like nephrotic disorder or glomerulonephritis may result in low total protein.

Other causes include extensive burns, malnutrition, bleeding, inflammation, or delayed post-surgery recovery.

High A/G Ratio

Experts consider the normal A/G ratio to be slightly higher than 1. This can be a symptom of health conditions of intestines, leukemia, liver, low thyroid levels, or kidney, or genetic diseases.

Low A/G Ratio

Total Protein Albumin to Globulin Ratio may be indicative of the presence of tumors in the bone marrow, or scarring and inflammation of the liver like cirrhosis. It can also be a sign of kidney disease or autoimmune disease that occurs when the immune system attacks the healthy cells of the body.

When Should You Repeat the Test?

If the TP blood test result is abnormal, additional blood tests may be requested to analyze the protein that is elevated or low, so that an accurate diagnosis can be made. In such circumstances, your doctor will probably compare the results of your blood test with that of your previous results, if any. 

If the doctor has doubts about the accuracy of the blood test results, they will advise you to get another TP test, or to take another blood test or urine test. For example, they may recommend a Serum Protein Electrophoresis (SPEP) if you have elevated levels of total serum protein.

Your doctor may also advise you to undertake the test in case there are other reasons for him/her to suspect that you may be suffering from a certain medical condition.

Procedure of the Total Protein Test

A medical practitioner draws blood from a vein, usually by inserting a needle from the back of the hand or from the inner side of the elbow. The blood is collected in the vial of the injection.

Then the sample undergoes a rigorous test under the microscope to generate the results. Drawing blood from newborns is done with a “heel stick” from a tiny puncture of the heel. The results of the TP test are available in about 10 hours. 

Learn more about diagnosing and managing kidney disease here.