Also Known As
Mast Cell Tryptase
Alpha Tryptase
Beta Tryptase
Mature Tryptase
Formal Name
Total Tryptase
This article was last reviewed on
This article waslast modified on 19 October 2018.
At a Glance
Why Get Tested?

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

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 professional suspects that you have mastocytosis or mast cell activation syndrome.

Sample Required?

A blood sample taken from a vein in your arm

Test Preparation Needed?

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

On average it takes 7 working days for the blood test results to come back from the hospital, depending on the exact tests requested. Some specialist test results may take longer, if samples have to be sent to a reference (specialist) laboratory. The X-ray & scan results may take longer. If you are registered to use the online services of your local practice, you will be able to access your results online.

If the doctor wants to see you about the result(s), you will be offered an appointment. If you are concerned about your test results, you will need to arrange an appointment with your doctor so that all relevant information including age, ethnicity, health history, signs and symptoms, laboratory and other procedures (radiology, endoscopy, etc.), can be considered.

Lab Tests Online-UK is an educational website designed to provide patients and carers with information on laboratory tests used in medical care. We are not a laboratory and are unable to comment on an individual's health and treatment.

Reference ranges are dependent on many factors, including patient age, gender, sample population, and test method, and numeric test results can have different meanings in different laboratories.

For these reasons, you will not find reference ranges for the majority of tests described on this web site. The lab report containing your test results should include the relevant reference range for your test(s). Please consult your doctor or the laboratory that performed the test(s) to obtain the reference range if you do not have the lab report.

For more information on reference ranges, please read Reference Ranges and What They Mean.

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 leukaemia.

How is the sample collected for testing?

A blood sample is obtained by inserting a needle into a vein in the arm.

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.

Accordion Title
Common Questions
  • How is it used?

    The tryptase test is a useful indicator of mast cell activation. Mast cells are large tissue cells present in highest amounts in the skin, the lining of the intestine and air passages, and the bone marrow. They release tryptase and other substances as part of the body's normal response to injury but also may release them as part of an allergic response. The tryptase test may be used:

    • To confirm a diagnosis of anaphylaxis. Anaphylaxis is primarily diagnosed clinically, but a total tryptase may be requested, to help confirm anaphylaxis as the cause of someone's acute symptoms. This is especially true if the person has recurrent episodes and/or if the diagnosis is uncertain.
    • To help diagnose mastocytosis (too many mast cells) or a mast cell activation disorder. Mastocytosis is a rare group of disorders associated with an abnormal increase in the number of mast cells, which may accumulate in the skin (cutaneous mastocytosis) or in organs throughout the body (systemic mastocytosis).

    Other tests may be used to evaluate a person's health status and to help rule out other conditions that can cause similar symptoms. These may include:

    Occasionally, a tryptase test may be performed postmortem to help determine if anaphylaxis was the cause of a person's death.

  • When is it requested?

    Tryptase is not a frequently requested test. The NICE guidelines for the management of suspected anaphylaxis state that a tryptase series of blood tests should be sent to the laboratory for testing in all cases . Mastocytosis is rare. Symptoms of anaphylaxis may include:

    • Flushing
    • Swelling of the throat, face, tongue, and/or eyes
    • Low blood pressure
    • Nausea, vomiting, diarrhoea, abdominal pain
    • Cardiac arrhythmias
    • Light-headedness or dizziness
    • Difficulty breathing, wheezing
    • Itching, often with visible hives
    • Confusion and/or loss of consciousness

    Many of these symptoms are also seen with other conditions.

    This test may also be requested when a healthcare professional suspects that a person may have cutaneous or systemic mastocytosis or a mast cell activation disorder. People with such conditions may have many of the same symptoms and signs as people with severe allergies but often without any specific trigger, such as exposure to a specific food (such as peanuts) or a bee sting. People with systemic mastocytosis may have symptoms that indicate organ involvement, such as peptic ulcers, chronic diarrhoea, and joint pain. There may be enlargement of organs such as the liver, spleen, or lymph nodes. There may be skin involvement with rashes or characteristic red, blistering lesions.

    A tryptase test may be requested after a person's death to help determine if anaphylaxis was the cause of death.

  • What does the test result mean?

    Acutely elevated tryptase concentrations in a person with symptoms of anaphylaxis indicate it as the likely diagnosis. A baseline sample for comparison is always required.

    Persistently elevated tryptase concentrations in a person with symptoms of mast cell activation suggest that the person has mastocytosis. Additional testing is required to confirm this diagnosis. Tryptase concentrations are thought to correlate with mast cell "burden" (quantity) in those with systemic mastocytosis.

  • Is there anything else I should know?

    Mast cells contain different forms of the enzyme tryptase, called alpha (α) and beta (β) tryptase, in both inactive and active (mature) forms. Laboratory testing can be performed to measure total tryptase, which is all of the forms together, or mature tryptase. In most cases, a total tryptase is requested, but sometimes both a total and mature tryptase may be requested and the ratio of the two compared. As the predominant mature tryptase in the blood is usually beta tryptase, this is essentially a comparison between total tryptase and beta tryptase. Total-to-mature tryptase ratios that are less than 10 are suggestive of anaphylaxis, while ratios greater than 20 are suggestive of systemic mastocytosis.

    If systemic mastocytosis is suspected, an elevated tryptase test result may be followed by a bone marrow aspiration and biopsy to determine if systemic mastocytosis is present. Typically, there are increased numbers of mast cells in the bone marrow in this disease.

    Tryptase can also be elevated with asthma, myelodysplastic syndrome (a type of bone marrow disorder), acute myelocytic leukaemia, and with any condition that activates mast cells.

    The release of tryptase from mast cells may be triggered by a wide variety of substances, but reaction to a food is thought to be the most common cause of anaphylaxis.

    Anyone can have mastocytosis, but children are more frequently affected with cutaneous mastocytosis. In children, mastocytosis is more likely to be self-limited and may be transient.

    Studies have linked genetic mutations with some cases of systemic mastocytosis. One of the common mutations identified is a codon-816 C-KIT mutation (CD117). Testing for this mutation is not routine but may occasionally be performed.

  • Can tryptase testing be done in my doctor's surgery?

    No, the tryptase test is a specialised blood test that is not offered in every laboratory and the sample will usually be sent to a reference laboratory for testing.

  • If I think I have an allergy, should I have a tryptase test done?

    Your healthcare professional may request specific allergy tests to help determine the substances you are allergic to, but a tryptase test would usually be done only if severe allergic symptoms are present. Most people with allergies will never need to have a tryptase test performed.

  • How is anaphylaxis treated?

    Anaphylaxis can be rapidly fatal and requires immediate medical treatment with injections of epinephrine and other medications. This is followed by careful monitoring as it is not uncommon for anaphylaxis to recur within a couple of days of the initial episode. Those who are known to have severe allergic reactions are encouraged to carry a kit that contains an emergency injection of epinephrine with them at all times.

  • If I have an elevated tryptase, does this mean I have mastocytosis?

    Not necessarily. Tryptase is just one of the criteria that your healthcare professional will consider before making a diagnosis of mastocytosis, which is a rare disorder.