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Tryptase

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Also known as: Mast Cell Tryptase; Alpha Tryptase; Beta Tryptase; Mature Tryptase
Formal name: Total Tryptase

At a Glance

Why Get Tested?

To help diagnose anaphylaxis, mastocytosis (too many mast cells), or mast cell activation

When to Get Tested?

When you have symptoms such as flushing, nausea, throat swelling, or low blood pressure that may be due to a life-threatening allergic reaction; when your healthcare provider suspects that you have mastocytosis or mast cell activation

Sample Required?

A blood sample drawn from a vein in your arm

Test Preparation Needed?

None, but timing of the sample soon after the beginning of symptoms can be important.

The Test Sample

What is being tested?

Tryptase is an enzyme that is released, along with histamine and other chemicals, from mast cells when they are activated as part of a normal immune response as well as in allergic (hypersensitivity) responses. This test measures the amount of tryptase in the blood.

Mast cells are large tissue cells found throughout the body. They are present in highest amounts in the skin, the lining of the intestine and air passages, and the bone marrow. They contain granules that store a number of chemicals, including tryptase and histamine. When mast cells are activated, they release their contents. If a person has too many mast cells (mastocytosis) and/or the cells are activated inappropriately, the chemicals that are released (especially histamine) may cause symptoms that range from moderate to life-threatening.

Normally, the level of tryptase in the blood is very low. When mast cells are activated, the level increases rapidly, rising within 15 to 30 minutes, peaking at 1 to 2 hours, and returning to normal after several hours to a couple of days. In people with severe allergies, activation of many mast cells can cause an extreme form of allergic reaction known as anaphylaxis, which can cause low blood pressure, hives (blisters on the skin), severe narrowing of the air passages, and even death. Tryptase levels will be very high in people with anaphylaxis.

In some cases, tryptase levels will be high in persons with mast cell activation disorders, in which mast cells become activated without apparent allergies or other reasons.

Tryptase levels can also be significantly and persistently increased with mastocytosis, a rare group of disorders associated with an abnormal increase in the number of mast cells. These cells may accumulate in the skin (cutaneous mastocytosis) or in organs throughout the body (systemic mastocytosis).

While cutaneous mastocytosis typically only causes skin problems (particularly hives), people with systemic mastocytosis or a mast cell activation disorder may experience anaphylaxis and its associated symptoms. These symptoms may be persistent and are related to the organs affected by mast cell accumulation. Systemic mastocytosis may progress slowly or may be aggressive, causing organ dysfunction and, in rare cases, causing a form of leukemia.

How is the sample collected for testing?

A blood sample is obtained by inserting a needle into 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, but timing of the sample soon after the beginning of symptoms can be important. Talk to your health practitioner about sample timing.

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

(Updated 2013 March 18). Systemic Mastocytosis. Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/203948-overview through http://emedicine.medscape.com. Accessed March 2014.

(Updated 2013 October 28). Mastocytosis. National Institute of Allergy and Infectious Diseases [On-line information]. Available online at http://www.niaid.nih.gov/topics/mastocytosis/Pages/Default.aspx through http://www.niaid.nih.gov. Accessed March 2014.

Medscape Editorial Staff et. al. (Updated 2012 October 3). Serum Tryptase. Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/2093911-overview#showall through http://emedicine.medscape.com. Accessed March 2014.

(© 1995–2014). Tryptase, Serum. Mayo Clinic Mayo Medical Laboratories [On-line information]. Available online at http://www.mayomedicallaboratories.com/test-catalog/Overview/81608 through http://www.mayomedicallaboratories.com. Accessed March 2014.

Delgado, J. (Reviewed 2014 January). Anaphylaxis. ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/Anaphylaxis.html?client_ID=LTD#tabs=0 through http://www.arupconsult.com. Accessed March 2014.

Kelley, T. (Reviewed 2013 September). Mast Cell Disease. ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/MastCellDz.html through http://www.arupconsult.com. Accessed March 2014.

Sources Used in Previous Reviews

Delgado, J. et. al. (Updated 2010 February). Anaphylaxis. ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/Anaphylaxis.html?client_ID=LTD# through http://www.arupconsult.com. Accessed May 2010.

Grenache, D. and Ho, A. (Updated 2009 November). Mast Cell Disease. ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/MastCellDz.html?client_ID=LTD through http://www.arupconsult.com. Accessed May 2010.

Delves, P. (Revised 2008 September). Mastocytosis. Merck Manual for Healthcare Professionals [On-line information]. Available online at http://www.merck.com/mmpe/sec13/ch165/ch165f.html?qt=tryptase&alt=sh through http://www.merck.com. Accessed May 2010.

Check, W. (2009 December). Allergy testing: from skin to tube to chip. CAP Today [On-line information]. Available online through http://www.cap.org. Accessed May 2010.

(© 1995–2010). Unit Code 91815: Tryptase, Mayo Clinic, Mayo Medical Laboratories [On-line information]. Available online at http://www.mayomedicallaboratories.com/test-catalog/Overview/91815 through http://www.mayomedicallaboratories.com. Accessed May 2010.

(© 1995–2010). Unit Code 81572: Tryptase, Immunostain. Mayo Clinic, Mayo Medical Laboratories [On-line information]. Available online at http://www.mayomedicallaboratories.com/test-catalog/Overview/81572 through http://www.mayomedicallaboratories.com. Accessed May 2010.

Peavy, R. and Metcalfe, D. (2008 September 22). Understanding the Mechanisms of Anaphylaxis. Medscape Today from Curr Opin Allergy Clin Immunol. 2008;8(4):310-314 [On-line information]. Available online at http://www.medscape.com/viewarticle/579500 through http://www.medscape.com. Accessed May 2010.

Hogan, D. and Martino, C. (Updated 2009 September 11). Mastocytosis. eMedicine [On-line information]. Available online at http://emedicine.medscape.com/article/1057932-overview through http://emedicine.medscape.com. Accessed May 2010.

Kemp, S. and Palmer, G.W. (Updated 2009 April 29). Anaphylaxis. eMedicine [On-line information]. Available online at http://emedicine.medscape.com/article/135065-overview through http://emedicine.medscape.com. Accessed May 2010.

Tharp, M. (© 2010). Mast Cells and Their Mediators. American Academy of Dermatology [On-line information]. Available online at http://www.aad.org/education/students/mastcells.htm through http://www.aad.org. Accessed May 2010.

Metcalfe, D. (2008 August). Mast cells and mastocytosis. Blood 15 August 2008, Vol. 112, No. 4, pp. 946-956 [On-line information]. Available online at http://bloodjournal.hematologylibrary.org/cgi/content/full/112/4/946 through http://bloodjournal.hematologylibrary.org. Accessed May 2010.

Krishnan, K. et. al. (Updated 2009 October 4). Mastocytosis, Systemic. eMedicine [On-line information]. Available online at http://emedicine.medscape.com/article/203948-overview through http://emedicine.medscape.com. Accessed May 2010.

Kasper DL, Braunwald E, Fauci AS, Hauser SL, Longo DL, Jameson JL eds, (2005). Harrison's Principles of Internal Medicine, 16th Edition, McGraw Hill, Pp 1950, 1953-1954.

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