What is Tryptase? High and low values | Lab results explained

This test measures the amount of tryptase in the blood.

Other names: 

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 responses. 

What are mast cells?

Mast cells, which are granulocytes found in peripheral tissue, play a central role in inflammatory and immediate allergic reactions. 

They are present in the highest amounts in:

  • the skin 
  • the lining of the intestine
  • air passages, 
  • and the bone marrow

They contain granules (=particles) 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.

Normal conditions:

Normally, the level of tryptase in the blood is very low. 

Higher levels:

  • 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 (=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.


  • Mast cell tryptase: a review of its physiology and clinical significance. [L]
  • Clinical significance of serum tryptase, Nam, Young-Hee et al., Journal of Allergy and Clinical Immunology, Volume 141, Issue 2, AB162 [L]
  • Patient Reported Symptoms and Tryptase Levels in WHO-Defined Systemic Mastocytosis (SM) Versus Mast Cell Activation Syndrome (MCAS) Versus Neither, Darci Zblewski, Ramy A. Abdelrahman, Dong Chen, Joseph H. Butterfield, Ayalew Tefferi, Animesh Pardanani, Blood Dec 2014, 124 (21) 3204 [L]


Test results may vary depending on your age, gender, health history, the method used for the test, and other things. Your test results may not mean you have a problem. Ask your healthcare provider what your test results mean for you.

The information on is NOT intended to replace a one-on-one relationship with a qualified health care professional and is not intended as medical advice.

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