Proteins perform critically important functions in your body. The cytoskeleton is an internal protein network that maintains cellular shape and physical integrity. Actin and myosin filaments allow your muscles to contract. Hemoglobin transports oxygen and circulates antibodies that fight foreign invaders in your body. Enzymes catalyze reactions that generate energy and synthesize and degrade biomolecules. Receptors enable your cells to respond to hormones and other cues.
Blood Proteins
Also called serum proteins, blood proteins are the proteins found in circulating blood. Laboratories can test for levels of different proteins such as albumin, globulins, fibrinogen, alpha-1 antitrypsin, lipoproteins and prothrombin. To assess the overall blood protein levels, doctors should measure the levels of albumin in your blood. Doctors typically measure albumin levels by performing a serum total protein test that also measures globulins.
Total Protein
Optimum protein levels will vary from person to person and your recommended values can change significantly if you suffer from a specific medical condition. Doctors typically find more value in knowing the blood protein level increase or decrease between tests than the value from a single test. The National Institutes of Health has established a normal range for blood protein levels of 6.0 to 8.3 g/dl. Your total protein levels can also diminish as a result of malnutrition and malabsorption, liver disease, diarrhea, severe burns, hormone imbalances that favor breakdown of tissue, loss through the urine in severe kidney disease, low albumin, low globulins and pregnancy.
Albumin
Albumin is synthesized in your liver using dietary protein. Albumin helps you maintain fluid volume within the vascular arteries, veins and lymphatics space. According to "Harper's Illustrated Biochemisty," the normal values of albumin range from 4.5 to 5.0 g/dL. Dehydration, hypothyroidism, chronic debilitating diseases, malnutrition, dilution by excess water, kidney losses, protein loss through the gastrointestinal tract, skin losses, liver dysfunction and insufficient anabolic hormones can reduce albumin levels in your body.
Globulins
Globulins are a type of protein that includes antibodies, enzymes and transporters. There are four groups of globulins, gamma globulins, beta globulins, alpha-2 globulins and alpha-1 globulins. According to "Harper's Illustrated Biochemisty," globulins have an optimal range of 2.3 to 2.8 g/dL. Nephrosis, Alpha-1 Antitrypsin deficiency, acute hemolytic anemia, liver dysfunction and hypogammaglobulinemia can cause low levels of globulins in your body.
References
- "Harper's Illustrated Biochemistry, 28th Edition (LANGE Basic Science)"; Robert Murray, et al; 2009
- Medline Plus: Total Protein
- "Proteins: Structures and Molecular Properties"; Thomas E. Creighton; 1992
- "Introduction to Protein Structure"; Carl Branden and John Tooze; 1999
- "Harrison's Principles of Internal Medicine"; Dennis Kasper, et al; 2004
