Total Protein, Albumin-Globulin (A/G) Ratio
When you have a routine health exam; when you experience unexpected weight loss or fatigue, or when your healthcare practitioner thinks that you could have symptoms of a liver or kidney disorder
A blood sample drawn from a vein or by fingerstick or, in the case of newborns, by heelstick
Proteins are important building blocks of all cells and tissues. They are important for body growth, development, and health. They form the structural part of most organs and make up enzymes and hormones that regulate body functions. This test measures the amount of protein in your blood.
Two classes of proteins are found in the blood, albumin and globulin.
- Albumin is made by the liver and makes up about 60% of the total protein. Albumin keeps fluid from leaking out of blood vessels, nourishes tissues, and transports hormones, vitamins, drugs, and substances like calcium throughout the body.
- Globulins make up the remaining 40% of proteins in the blood. The globulins are a varied group of proteins, some produced by the liver and some by the immune system. They help fight infection and transport nutrients.
The test also compares the amount of albumin with globulin and calculates what is called the A/G ratio. A change in this ratio can provide your healthcare practitioner with a clue as to the cause of the change in protein levels.
Total protein levels in the blood may increase or decrease, to a greater or lesser degree, with various conditions.
Total protein levels may decrease in conditions that:
- Interfere with production of albumin or globulin proteins, such as malnutrition or severe liver disease
- Increase the breakdown or loss of protein, such as kidney disease (nephrotic syndrome)
- Increase or expand the volume of plasma, the liquid part of blood (diluting the blood), such as congestive heart failure
Total protein levels may increase with conditions that cause:
How is the test used?
These tests may also be used to help diagnose diseases and to monitor conditions or treatments. Total protein levels can be affected by many different diseases and disorders. For example, a total protein test may be used to help diagnose kidney disease or as part of a liver panel to help detect liver disease.
Results may indicate the need further testing. If total protein is abnormal, your healthcare practitioner may recommend follow-up tests, such as protein electrophoresis and quantitative immunoglobulins.
Some laboratories report total protein, albumin, and also the calculated ratio of albumin to globulins, the A/G ratio. The A/G ratio may provide a clue as to the cause of the change in protein levels.
When is it ordered?
A total protein test is frequently ordered as part of a comprehensive metabolic panel (CMP) when you have a routine health checkup.
What does the test result mean?
Results of a total protein test are evaluated along with those from other tests of the CMP. If results are abnormal, further tests are required to identify which protein is high or low before your healthcare practitioner can make a diagnosis.
Some examples of conditions that cause low total protein include:
- Liver disorder
- Kidney disorder
- A disorder in which protein is not digested or absorbed properly
- Malabsorption such as celiac disease or inflammatory bowel disease (IBD)
Some examples of conditions that cause high total protein include:
- Chronic inflammation or infections such as viral hepatitis or HIV
- Bone marrow disorders such as multiple myeloma
Low A/G ratio may be caused by:
- Overproduction of globulins, such as seen in multiple myeloma or autoimmune diseases
- Underproduction of albumin, such as may occur with cirrhosis
- Selective loss of albumin from the circulation, as may occur with kidney disease (nephrotic syndrome)
High A/G ratio may be caused by:
Will a high protein diet raise my total protein level?
What type of nutrition is recommended for optimal protein levels?
What are globulin proteins and how are they measured in blood?
Globulins are a group of proteins in the blood, some produced by the liver and some by the immune system. They help fight infection and transport nutrients. There are four main types: alpha 1, alpha 2, beta, and gamma. They are measured using different tests:
- Total protein test—measures albumin and globulin
- Serum protein electrophoresis—can be used to measure the different groups of globulin proteins
Can protein be measured in samples other than blood?
Is there anything else I should know?