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Understanding Tryptase Levels: What Your Allergy Screening Results Mean

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Introduction

Do you experience symptoms like itching, hives, wheezing or abdominal pain and wonder if you may have an allergy? Tryptase levels measured through a simple blood test can provide valuable clues. Tryptase is an enzyme released by mast cells, which play a central role in allergic reactions. Knowing your tryptase levels can help diagnose mast cell disorders and assess your allergy risk. This article will explain what tryptase levels indicate, the difference between normal and elevated tryptase levels, and how to interpret your allergy screening results. Armed with this knowledge, you can work with your doctor to manage allergies and mast cell conditions more effectively.

What is Tryptase?

Tryptase is a protein enzyme secreted by mast cells, a type of white blood cell involved in the body's allergic and inflammatory responses. Mast cells are found in connective tissues throughout the body, especially in areas that come into contact with the external environment, such as the skin, respiratory tract and digestive system. When mast cells are activated by an allergen or other trigger, they rapidly release inflammatory chemicals including histamine and tryptase into the bloodstream and surrounding tissues. This causes allergy symptoms like redness, swelling, itching and airway constriction. Tryptase levels in the blood can indicate the extent of mast cell activation.

Normal Tryptase Levels

In healthy adults, the normal tryptase level typically ranges from 1 to 15 ng/mL. This normal reference range includes people with a genetic condition called hereditary alpha tryptasemia (HαT), who have extra copies of the alpha tryptase gene. By using this broader definition of normal tryptase levels, doctors can avoid causing undue worry in patients whose levels are only slightly elevated due to genetics rather than an active mast cell disorder.

Elevated Tryptase Levels

A tryptase level above 15 ng/mL is considered elevated and may point to a mast cell activation disorder such as:

  • Systemic mastocytosis (SM): A rare condition involving the excessive accumulation of abnormal mast cells in body tissues
  • Mast cell activation syndrome (MCAS): Episodic mast cell activation with little to no increase in mast cell numbers
  • Hereditary alpha tryptasemia (HαT): Inherited extra copies of the alpha tryptase gene, leading to chronically elevated tryptase

Common Causes of Elevated Tryptase

Several factors can contribute to increased mast cell activity and elevated tryptase levels, including:

  1. Allergic disorders like allergic rhinitis, asthma, food allergies and stinging insect allergies
  2. Inflammatory conditions such as inflammatory bowel disease (IBD) and rheumatoid arthritis
  3. Infections, physical stressors, temperature changes and exposure to toxins or venoms
  4. Certain medications like opioids, NSAIDs and radiocontrast agents

In systemic mastocytosis, a KIT gene mutation causes mast cells to grow and accumulate abnormally in the skin, bone marrow, gastrointestinal tract and other organs. This leads to persistent symptoms and greatly elevated tryptase levels, often above 20 ng/mL.

Symptoms Associated with High Tryptase

Elevated tryptase levels often correlate with symptoms of mast cell activation, which can affect multiple organ systems:

  • Skin: Itching, flushing, hives, swelling and skin rashes
  • Respiratory: Wheezing, shortness of breath, cough and nasal congestion
  • Gastrointestinal: Abdominal pain, bloating, diarrhea, nausea and vomiting
  • Cardiovascular: Rapid heartbeat, low blood pressure and fainting
  • Neurological: Headache, anxiety, difficulty concentrating and sleep disturbances

Anaphylaxis, a severe multi-system allergic reaction, is the most dangerous consequence of mast cell activation and can be life-threatening if not promptly treated with epinephrine.

Low Tryptase Levels

Low tryptase levels, below 1 ng/mL, are less common and not typically a cause for concern. They may indicate low mast cell numbers or decreased mast cell activity due to medications that stabilize mast cells, like antihistamines and mast cell inhibitors. However, in rare cases, very low tryptase levels could signal an immune deficiency that impairs mast cell development. If you have low tryptase on repeated tests without a clear cause, consult an immunologist for further evaluation.

Interpreting Your Allergy Screening Results

When interpreting tryptase levels, doctors consider both the absolute tryptase level and the pattern of tryptase over time, along with your clinical history and symptoms. Some key points to keep in mind:

  • Tryptase levels above 20 ng/mL, especially with characteristic symptoms, strongly suggest systemic mastocytosis. The diagnosis can be confirmed through bone marrow biopsy and testing for KIT gene mutations.
  • In mast cell activation syndrome, the tryptase level is often normal or only slightly elevated between episodes, but rises significantly (often >20 ng/mL) during a flare. Tracking your tryptase levels over time, along with a symptom diary, can help identify triggers.
  • Hereditary alpha tryptasemia is characterized by a chronically elevated tryptase level (>8 ng/mL), but usually <20 ng/mL, in the absence of other criteria for systemic mastocytosis. Genetic testing can confirm extra copies of the alpha tryptase gene.

Tryptase Levels During Allergy Testing

Tryptase is routinely measured during allergy testing to assess for mast cell activation disorders. Two types of tryptase tests are commonly used:

  1. Baseline serum tryptase: A blood test that measures your tryptase level at a single point in time. It is most useful for diagnosing mastocytosis and monitoring response to treatment. The blood sample should be drawn when you are not having an acute allergic reaction.
  2. Acute serum tryptase: A series of 3 blood tests performed within 4 hours of the start of anaphylaxis symptoms, with a baseline level checked >24 hours later for comparison. An acute tryptase level more than 2 ng/mL + 1.2 x baseline confirms mast cell activation was likely responsible for the anaphylactic episode.

What Results Mean for You

If your allergy screening reveals an elevated tryptase level, your doctor will perform additional testing to pinpoint the underlying cause. This may include:

  • Bone marrow biopsy and KIT gene analysis to evaluate for systemic mastocytosis
  • 24-hour urine test for mast cell mediators like histamine and prostaglandins
  • Imaging studies to check for organ enlargement or damage related to mast cell infiltration
  • Food and medication challenges to identify specific triggers

Once diagnosed, mast cell disorders are managed through a combination of trigger avoidance, rescue medication (antihistamines, epinephrine autoinjector), and preventive therapies that reduce mast cell activity over time. In severe cases of mastocytosis, chemotherapy may be needed.

Managing Allergies and Mast Cell Disorders

If you have allergies or a mast cell disorder, work with your doctor to develop a comprehensive management plan:

  • Learn to recognize and avoid your triggers, such as certain foods, medications, insect stings, and environmental irritants.
  • Always carry an epinephrine autoinjector and know how to use it in case of anaphylaxis.
  • Take antihistamines and mast cell stabilizers as prescribed to prevent and relieve symptoms.
  • Consider immunotherapy (allergy shots or tablets) to reduce sensitivity to airborne allergens.
  • Adopt stress management techniques, as stress can exacerbate mast cell activation.

Treatment Options for Elevated Tryptase Levels

The treatment approach for elevated tryptase levels depends on the specific diagnosis:

  • Systemic mastocytosis: Antihistamines, mast cell stabilizers, leukotriene modifiers and tyrosine kinase inhibitors can help control symptoms. Aggressive subtypes may require chemotherapy or stem cell transplant.
  • Mast cell activation syndrome: Treatment focuses on identifying and avoiding triggers, and using medications like H1 and H2 antihistamines, mast cell stabilizers, antileukotrienes and oral cromolyn sodium to prevent mast cell degranulation.
  • Hereditary alpha tryptasemia: Management is similar to mast cell activation syndrome, with trigger avoidance, antihistamines and epinephrine for acute reactions. Aspirin therapy may reduce the risk of severe reactions in some patients.

Preventing Future Allergic Reactions

Knowing your allergies and tryptase level is key to preventing severe reactions in the future. Take these precautions:

  • Strictly avoid identified food allergens and triggers. Read labels carefully and inform restaurants of your allergies.
  • Carry an epinephrine autoinjector at all times and ensure family and friends know how to administer it.
  • Wear a medical alert bracelet indicating your allergies and mast cell disorder.
  • Stay up-to-date on vaccinations, including the annual flu shot, to reduce infection-triggered reactions.

FAQ

How are tryptase levels tested?

Tryptase is measured through a simple blood test. The blood sample is usually drawn from a vein in your arm and sent to a lab for analysis. No special preparation is needed before the test.

Can stress affect tryptase levels?

Yes, emotional stress and anxiety can trigger mast cell activation and increase tryptase levels. Managing stress through relaxation techniques, meditation, exercise and counseling may help control symptoms in people with mast cell disorders.

What is the difference between baseline and acute tryptase levels?

Baseline tryptase is a snapshot of your mast cell activity at a single point in time, when you are not having an allergic reaction. It helps diagnose mastocytosis and mast cell activation syndrome. Acute tryptase is measured shortly after anaphylaxis symptoms begin and reflects mast cell degranulation during the reaction. A significantly higher acute level confirms anaphylaxis.

When to see a doctor

See your doctor if you experience symptoms suggestive of mast cell activation, such as:

  • Recurrent unexplained flushing, itching, hives or swelling
  • Worsening or poorly controlled asthma
  • Frequent abdominal pain, diarrhea or nausea
  • Dizziness or fainting spells
  • Anaphylaxis (severe allergic reaction involving more than one organ system)

Keep a diary of your symptoms along with any suspected triggers to help your doctor make an accurate diagnosis. If you have a known mast cell disorder, consult your doctor regularly to ensure your treatment plan is keeping symptoms well controlled.

Conclusion

In summary, tryptase levels provide a window into mast cell activity and can help diagnose allergic and mast cell disorders. Knowing whether you have normal, elevated or low tryptase levels guides your doctor in pinpointing the underlying cause and developing an appropriate treatment plan. With proper diagnosis and management, people with mast cell disorders can minimize symptoms and lead full, active lives. If you suspect you may have a mast cell condition, don't hesitate to consult an allergy specialist.

At Metropolis Healthcare, we understand the challenges faced by those with allergies and mast cell activation. Our team of skilled phlebotomists provides convenient at-home blood draws for tryptase and other allergy tests, with samples expertly analyzed in our state-of-the-art labs. We deliver your results securely online via email and our user-friendly app, so you and your doctor can make informed decisions about your care. To learn more about our allergy testing.

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