At a Glance
Why Get Tested?
When to Get Tested?
When you have a routine physical exam or when you experience unexpected weight loss or fatigue, or when your doctor thinks that you have symptoms of a liver or kidney disorder
A blood sample drawn from a vein in your arm or by fingerstick (adults and children) or heelstick (newborns)
Test Preparation Needed?
The Test Sample
What is being tested?
Proteins are important building blocks of all cells and tissues; they are important for body growth, development, and health. They form the structural part of most organs and make up enzymes and hormones that regulate body functions. This test measures the total amount of the various types of proteins in the liquid (plasma) portion of the blood.
Two classes of proteins are found in the blood, albumin and globulin. Albumin makes up about 60% of the total protein. Produced by the liver, albumin serves a variety of functions including as a carrier protein for many small molecules and ions, as a source of amino acids for tissue metabolism, and as the principle component involved in maintaining osmotic pressure (preventing fluid from leaking out of blood vessels). The remaining 40% of proteins in the plasma are referred to as globulins. The globulin proteins are a heterogeneous group. They include enzymes, antibodies, hormones, carrier proteins, and numerous other types of proteins. The ratio of albumin to globulin (A/G ratio) is calculated from measured albumin and calculated globulin (total protein - albumin).
The level of total protein in the blood is normally a relatively stable value, reflecting a balance in loss of old protein molecules and production of new protein molecules.
Total protein may decrease in conditions:
- Where production of albumin or globulin proteins is impaired, such as malnutrition or severe liver disease
- That accelerate the breakdown or loss of protein, such as kidney disease (nephrotic syndrome)
- That increase/expand plasma volume (diluting the blood), such as congestive heart failure
Total protein may increase with conditions that cause:
The A/G ratio may change whenever the proportions of albumin and other proteins shift (increase or decrease) in relationship to each other.
How is the sample collected for testing?
A blood sample is obtained by inserting a needle into a vein in the arm or by a fingerstick (for children and adults) or heelstick (for newborns).
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.
Ask a Laboratory Scientist
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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.
Sources Used in Current Review
Dugdale, D. (Updated 2011 May 30). Total protein. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003483.htm. Accessed February 2013.
(© 1995–2013). Protein, Total, Serum. Mayo Clinic Mayo Medical Laboratories [On-line information]. Available online at http://www.mayomedicallaboratories.com/test-catalog/Overview/8520 through http://www.mayomedicallaboratories.com. Accessed February 2013.
Alvaran Tuazon, S. and Scarpaci, A. (Updated 2012 May 11). Serum Protein Electrophoresis. Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/2087113-overview#showall through http://emedicine.medscape.com. Accessed February 2013.
Gersten, T. (Updated 2012 February 8). Protein electrophoresis – serum. MedlinePlus Medical Encyclopedia [On-line information]. Available online at [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003540.htm. Accessed February 2013.
Pagana, K. D. & Pagana, T. J. (© 2011). Mosby's Diagnostic and Laboratory Test Reference 10th Edition: Mosby, Inc., Saint Louis, MO. Pp 799-804.
Clarke, W., Editor (© 2011). Contemporary Practice in Clinical Chemistry 2nd Edition: AACC Press, Washington, DC. Pp 233-246.
Sources Used in Previous Reviews
Thomas, Clayton L., Editor (1997). Taber's Cyclopedic Medical Dictionary. F.A. Davis Company, Philadelphia, PA [18th Edition].
Pagana, Kathleen D. & Pagana, Timothy J. (2001). Mosby's Diagnostic and Laboratory Test Reference 5th Edition: Mosby, Inc., Saint Louis, MO.
Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. Burtis CA, Ashwood ER and Bruns DE, eds. 4th ed. St. Louis, Missouri: Elsevier Saunders; 2006, Pp 543-546.
(May 17, 2007) Van Voorhees B. MedlinePlus Medical Encyclopedia. Total Protein. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003483.htm. Accessed April 2009.
Henry's Clinical Diagnosis and Management by Laboratory Methods. 21st ed. McPherson RA and Pincus MR, eds. Philadelphia: 2007, Pp 231-236.
(November 3, 2007) Mayo Clinic: High protein in blood: What causes it? Available online at http://www.mayoclinic.com/health/protein-in-blood/AN01204 through http://www.mayoclinic.com. Accessed April 2009.
Clarke, W. and Dufour, D. R., Editors (2006). Contemporary Practice in Clinical Chemistry. AACC Press, Washington, DC Pp 200, 206.