Serum protein is the amount of proteins present in blood plasma. In the blood plasma, protein is found in two forms namely albumin and globulin. Proteins in blood plasma have many functions such as transport of lipids, vitamins, hormones, and metals in body. They also help in regulating acellular activity. Moreover, proteins in blood plasma help in the functioning of immune system.
Some blood proteins serve as enzymes and others act as protease inhibitors. Hemoglobin itself is not a blood protein and is carried inside the red cells and not in the blood serum. The blood serum is made up of albumin, which forms the largest composition of the blood proteins. This accounts for close to 55 percent of blood proteins.
The role of albumin is to transport lipids and steroid hormones throughout the circulation system to other parts of the body. On the other hand, globulins consist of about 38 percent of blood proteins. This substance is responsible for transportation of hormones, lipids, ions, and assists in the immune function.
About 7 percent of blood protein occurs in form of fibrinogen. In the process of blood clotting, fibrinogen is converted to fibrin, which is an insoluble substance to help in clotting. A small percentage, about 1 percent of blood proteins consists of regulatory proteins like hormones, enzymes, and pro enzymes. Blood proteins are produced in the liver apart from the gamma globulins.
Total serum protein test
A total serum protein test is performed to measure the concentration of protein in blood plasma. This test is also used to measure the amount of the two forms of proteins in blood plasma, that is, albumin and globulin. Albumin is synthesized in liver and helps in keeping the blood inside the vessels and preventing it from leaking out of the vessels.
Albumin also assists in the transportation of medicines and other substances in blood. It as well helps in growth and healing of tissue. Globulin consists of different proteins, which are; alpha, beta, and gamma. Whereas some globulin binds with hemoglobin, other globulins help in transporting metals like iron in blood. They also help in fighting infection through the immune system. Separation of serum proteins through the process of electrophoresis is helpful both diagnosis as well as a clinical monitoring.
Albumin test is done to check how the liver and kidneys are functioning. It is also done to establish if the diet you are taking has sufficient proteins for the health of the body. Albumin tests may be performed to help in determining the cause of edema, or swelling of ankles, ascites or swelling of abdomen and collection of fluid in lungs or pulmonary edema.
Moreover, globulin test may be done to help determine the chances of suffering an infection. The test may also help in finding if a patient has a blood disease like macroglobulinemia and multiple myeloma. The tests for total serum protein may be broken down into total protein, albumin, alpha-1 globulin, alpha-2 globulin, and beta globulin.
The normal values of total proteins in blood plasma range from 6.4 to 8.3 grams per deciliter. The normal levels of albumin range from 3.5 to 5.0 grams per deciliter. Alpha-1 globulin levels range from 0.1 to 0.3g/dl, alpha 2 globulin- 0.6 to 1.0 g/dl, and beta globulin- 0.7 to 1.1 g/dl. These readings can vary from one laboratory to another.
Causes of high levels of serum proteins
The general causes of changes in serum total protein may be due to change in the plasma water volume and the concentration of any one or more of the specific blood plasma proteins. Albumin is particularly present in high concentrations in an individual and therefore if there are low levels of this protein substance, it may lead to a condition known as hypoproteinemia.
A decrease on the volume of plasma water or hemoconcentration may lead to some degree of hyperproteinemia. When hemodilution occurs, it may result to some degree of hypoproteinemia. When there is inadequate water intake or excessive water loss in body, these situations may lead to hyperproteinemia. Conditions like diarrhea, vomiting, and Addison’s disease may cause excessive loss of water. Increased production of proteins may also lead to hyperproteinemia.
High albumin levels could be caused by severe dehydration. High globulin levels may arise due to presence of diseases of the blood like multiple myeloma and hemolytic anemia. Other conditions like autoimmune disease including lupus, rheumatoid arthritis, and sarcoidosis may also lead to high globulin levels. Other diseases like kidney disease, tuberculosis, and liver disease are also associated with high globulin.
Low levels of albumin could be caused by poor diet or malnutrition, liver disease, kidney disease, and autoimmune diseases like lupus and rheumatoid arthritis. Hyperthyroidism, heart failure, uncontrolled diabetes, and gastrointestinal malabsorption syndromes like crohn’s disease also cause low levels of albumin. Total serum protein may increase during pregnancy.