To understand what plasma proteins are, one must first understand what plasma is. Blood contains plasma, which is nothing more than the liquid portion of the blood. It consists of more than 90 percent water, which is necessary for hydrating body tissues. About seven percent of plasma is made of proteins, which fall into one of three types.
Albumins are the most abundant of the plasma proteins, accounting for about 60 percent of all the proteins. They are manufactured by the liver, and are responsible for transporting various substances in the blood, including drugs. They also helps maintain water balance and contribute to osmotic pressure, which in simple terms is the pressure exerted by water moving by osmosis in and out of cells.
The globulin proteins include enzymes, protein carriers, and gamma globulin, or antibodies, something the body produces to fight infection and disease. While most plasma proteins are made in the liver, gamma globulins are made by lymphocytes called plasma cells. Globulins fall into one of four groups based on their size and electrical charge: gamma, beta, alpha-1 and alpha-2.
The sole function of fibrinogen (also called Factor I), another plasma protein produced by the liver, is to produce clots to help stop bleeding. It is a sticky, fibrous coagulant found in the blood that produces thrombin, that in turn converts to fibrin, the main protein in a blood clot. People with hemophilia (the "bleeding disease") are said to have Factor I deficiency. Afibrinogenemia is a complete absence of fibrinogen and is the most serious form of hemophilia. Hypofibrigenemia is lower-than-normal levels of fibrinogen and may produce moderate bleeding problems. Dysfibrinogenemia is when fibrinogen levels are normal but the protein does not function properly. People who suffer from this form of Factor I deficiency rarely have a problem clotting and may even clot abnormally.
Why Plasma Proteins are Important
Acting together, the three type of plasma proteins keep the body healthy. They are the building blocks of all the body's cell and tissue, including antibodies, hormones, and clotting agents. They transport a variety of substances, including drugs, hormones and vitamins. They control osmotic pressure between blood and tissues and help control the acid-alkaline balance of the blood. They are also a source of energy for muscles and tissues when not enough energy-producing foods are ingested.
Impact of Abnormal Plasma Proteins
Low albumin can indicate liver disease or kidney disease, which allows albumin to get into the urine, but are also explained by pregnancy (when albumin is naturally decreased), malnutrition, extensive burns or Crohn's disease. High albumin levels could be the result of dehydration or congestive heart failure.
High globulin levels can indicate chronic infection, liver disease or rheumatoid arthritis. Low levels might mean acute anemia, liver dysfunction or emphysema.
Elevated levels of fibrinogen seem to indicate an increased risk of stroke, one of the leading causes of death. Combined with high blood pressure, the risk is even greater. Exercise, not smoking, maintaining a healthy weight and medication seem to lower fibrinogen levels in the short term. Lower levels of fibrinogen indicate a form of hemophilia. This condition is inherited and affects both genders and all races and ethnicities.