Your liver is one of the largest organs in your body and primarily is involved in metabolism, digestion, detoxification and elimination of various harmful compounds from your body. Because your liver is in constant contact with toxins and responsible for metabolizing them or filtering them from your blood, it is particularly susceptible to damage, which is clearly illustrated by the connection between alcoholism and liver cirrhosis. When your liver is damaged, its production of enzymes and protein becomes imbalanced, which blood tests can detect.
Total Protein Test
Total protein is a rough measure of the protein that circulates in your blood. A total protein test is one component of a comprehensive metabolic panel, or CMP, of your blood that your doctor routinely orders as part of a health checkup. Total protein measurements of your blood can reflect nutritional status and are used to screen for and help diagnose liver and kidney diseases, as well as other health conditions. Sometimes an abnormal level of protein in your blood is detected well before symptoms of liver or kidney disease begin to appear. If total protein levels are abnormal, further testing is done to identify which specific protein is too low or too high so that an accurate diagnosis can be made.
Types of Protein
In general, total protein tests examine the amount and ratio of albumin and globulin, which are molecules made of protein. Albumin is made in your liver and is the most abundant protein in your blood plasma. It is important for transporting blood constituents and keeping fluid inside your blood vessels based on the principles of osmosis. Globulin is also made in the liver and is used as a building block for antibodies and other proteins involved in the clotting process. Disease conditions can cause total protein levels to be too high or too low. Furthermore, the albumin-to-globulin ratio is usually examined and normally will be over 1 because albumin tends to be more abundant in blood.
High Protein Levels
Your total protein should be between 6.3 and 8.2 g/dL of blood under healthy circumstances, according to the “Pocket Guide to Diagnostic Tests." High total protein levels are commonly caused by chronic inflammatory conditions or infections, such as viral hepatitis or HIV. Hepatitis A, B and C are all thought to be viral in origin. High protein levels might also be caused by osteolytic cancers such as multiple myeloma. A high albumin-to-globulin ratio often suggests reduced production of immunoglobulins, which occurs in genetic disorders and leukemia.
Low Protein Levels
Low total protein levels often suggest a primary liver or kidney disease, or severe malnutrition or malabsorption disorders such as celiac disease and inflammatory bowel syndrome. Low albumin also occurs with tissue damage from physical trauma. A low albumin-to-globulin ratio might reflect an autoimmune disease or reduced production of albumin, which occurs with liver cirrhosis. Kidney disease also causes low albumin levels. Low protein levels in your blood often lead to abnormal pooling of fluid in the abdomen or legs and is referred to as edema.
- LabTestsOnline.org: Total Protein and A/G Ratio
- “Functional Biochemistry in Health and Disease”; Eric Newsholme et al; 2010
- “Pocket Guide to Diagnostic Tests”; D. Nicoli et al.; 2001