The human body contains many thousands of different types of proteins. Each protein has its own job to do, such as clotting blood, regulating metabolism, and fighting off bacterial and viral infections. The total protein blood test measures the amount of all proteins found in the liquid part of the blood. An elevated level of protein in the blood may indicate inflammation, infection, a bone marrow disorder or other conditions.
High Protein in the Blood
A high total protein level can be the result of chronic inflammation or infection, such as with viral hepatitis or HIV, a bone marrow disorder like multiple myeloma, or dehydration. Total protein can also be increased during pregnancy. Certain drugs can increase total protein including insulin, progesterone, growth hormones, and steroids. A tourniquet applied for too long during blood collection may also falsely elevate total protein. Additional testing maybe required to determine the specific cause of the elevated protein level.
Dehydration can occur from not drinking enough water, severe vomiting, or diarrhea. This loss of water can affect the volume of the liquid part of the blood. Due to loss of fluid, all the proteins in the blood become concentrated and make the total protein level in the blood appear to be high.
Infection and Chronic Inflammation
A high total protein blood test may be caused by an infection or inflammation. Proteins from the immune system that are typically at low levels in the blood become increased when fighting off an infection, during inflammation, or when tissues are damaged by trauma or surgery. These proteins are called acute phase proteins and are typically produced by the liver as a nonspecific response to injury or inflammation. Antibodies, produced by the immune system in response to infection, are another type of protein which can increase total protein levels. Continuous antibody production is also characteristic of chronic inflammatory conditions. High total protein resulting from chronic inflammation can occur during autoimmune diseases such as rheumatoid arthritis or lupus (systemic lupus erythematosus). Infection with hepatitis B or C can cause chronic hepatitis resulting in ongoing inflammation and damage to the liver. According to a 2010 study published in "African Health Sciences," HIV is also a chronic infection causing inflammation which may result in high protein in the blood (see Reference 2).
Bone Marrow Disorders
Multiple myeloma is a cancer of plasma cells. Plasma cells are a type of white blood cell that can be found in your bone marrow which makes antibodies. In multiple myeloma, a plasma cell begins to grow out of control and produces high amounts of antibody. This increase in antibody production increases the total protein in the blood. Sometimes these cells can produce high levels of antibodies without being cancerous. This condition is called monoclonal gammopathy of undetermined significance (MGUS). Waldenstrom macroglobulinemia is very similar to multiple myeloma in that it is a cancer of a white blood cell producing high amounts of antibody however, the white blood cell involved is a B cell instead of a plasma cell.
Normal Values for Total Protein in Blood
A total protein blood test is typically done as part of a routine physical or to help diagnose nutritional problems, kidney disease, or liver disease. The amount of protein found in normal blood is relatively stable and according to the fourth edition of "Tietz Textbook of Clinical Chemistry and Molecular Diagnostics," ranges from 6.4 to 8.3 g/dL in adults (see Reference 3, Results found on page 2293, Table 56-1). Normal ranges vary slightly between laboratories.