Prealbumin

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Also known as: PA; Tryptophan-rich prealbumin; Thyroxine-binding prealbumin; TBPA
Formal name: Transthyretin test
Related tests: Albumin; Transferrin

At a Glance

Why Get Tested?

To help diagnose malnutrition and to monitor people at risk for poor nutrition

When to Get Tested?

When your doctor suspects that you are malnourished because of poor diet, HIV, or an eating disorder; when you are admitted to the hospital for surgery or certain diseases; or when you are having parenteral (for example, intravenous) nutrition or hemodialysis

Sample Required?

A blood sample drawn from a vein in the arm

Test Preparation Needed?

None

The Test Sample

What is being tested?

The test measures levels of prealbumin in the blood. Prealbumin is a protein produced primarily by the liver. It serves as a source of amino acids for the production of other proteins, and it carries substances such as the thyroid hormone thyroxine throughout the body. Prealbumin has a half-life of only two days, which means that it breaks down quickly in the body and the amount changes rapidly, decreasing when there is a protein deficiency. This short half-life gives doctors a snapshot of a person's current nutritional status.

How is the sample collected for testing?

A blood sample is taken by a needle from a vein in the arm.

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.

The Test

Common Questions

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Article Sources

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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

Pagana, K. D. & Pagana, T. J. (© 2007). Mosby's Diagnostic and Laboratory Test Reference 8th Edition: Mosby, Inc., Saint Louis, MO. Pp 755-756.

Clarke, W. and Dufour, D. R., Editors (© 2006). Contemporary Practice in Clinical Chemistry: AACC Press, Washington, DC. Pp 197.

Banh, L. (2006 October). Serum Proteins as Markers of Nutrition: What Are We Treating? Practical Gastroenterology [On-line information]. PDF available for download at http://www.healthsystem.virginia.edu/internet/digestive-health/nutritionarticles/BanhArticle.pdf through http://www.healthsystem.virginia.edu. Accessed June 2009.

Huckleberry, Y. (2004 May 03). Nutritional Support and the Surgical Patient. Medscape Today from American Journal of Health-System Pharmacy [On-line information]. Available online at http://www.medscape.com/viewarticle/474066 through http://www.medscape.com. Accessed June 2009.

Beck, F. and Rosenthal, T. (2002 April 15). Prealbumin: A Marker for Nutritional Evaluation. American Family Physician [On-line information]. Available online at http://www.aafp.org/afp/20020415/1575.html through http://www.aafp.org. Accessed June 2009.

Cassels, C. (2005 December 20). Hemodialysis, Prealbumin an independent predictor of mortality/morbidity. Medscape Medical News [On-line information]. Available online at http://www.medscape.com/viewarticle/538923 through http://www.medscape.com. Accessed June 2009.

Sources Used in Previous Reviews

The National Kidney Foundation: Kidney Disease Outcomes Quality Initiative. Available online at http://www.kidney.org/professionals/doqi/guidelines/nut_a04.html through http://www.kidney.org.

Holland DC, Meers C, Lawlor ME, Lam M. Serial prealbumin levels as predictors of outcomes in a retrospective cohort of peritoneal and hemodialysis patients. Journal of Renal Nutrition, July 2001, 11(3).

National Kidney Foundation Work Group, Committee: National Kidney Foundation-Kidney Disease Outcomes Quality Initiative. Clinical practice guidelines for nutrition in chronic renal failure. American Journal of Kidney Disease, June 2000, 35(6 Suppl 2): S1-140.

Clinical Guide to Laboratory Tests. 3rd ed. Tietz N, ed. Philadelphia: W.B. Saunders & Co; 1995: 608-609.

Frey RJ. Anorexia nervosa. Gale Encyclopedia of Medicine. Gale Research, 1999.

Larry A. Broussard, PhD. Clinical Laboratory Sciences, LSU Health Sciences Center, New Orleans, LA.