Tryptase Blood Test

What is tryptase?

Tryptase is an enzyme primarily found in mast cells, a type of white blood cell involved in the immune system. When mast cells are activated, such as during an allergic reaction or anaphylaxis, they release tryptase along with other substances like histamine. Tryptase plays a role in the inflammatory response, and elevated levels of tryptase in the blood can indicate mast cell activation, helping in the diagnosis of conditions such as mastocytosis (a disorder where there's an abnormal amount of mast cells) or severe allergic reactions.

What is a Tryptase Blood Test?

This test quantifies the presence of tryptase in the bloodstream. Tryptase, an enzyme released in conjunction with histamine and other compounds, is released from mast cells when they undergo activation as part of an allergic immune reaction.

Mast cells are distributed throughout the body yet are more commonly found in the skin, intestinal lining, air passages, and bone marrow, and contribute to the body's response to injury and allergic reactions. These mast cell granules contain various chemicals, including tryptase and histamine, which are discharged upon mast cell activation. The recognition and binding of IgE, a specific antibody often elevated in individuals with allergies and parasitic infections, triggers mast cell activation when IgE bound to mast cell surfaces attaches to its antigenic target. As a consequence of this, mast cells release their stored contents, particularly histamine, which generates numerous allergy-related symptoms.

Tryptase exists in diverse forms within mast cells, referred to as alpha and beta tryptase, both in inactive (protryptase) and active states. In the body, beta tryptase typically represents the primary mature form of tryptase. Testing options encompass measuring total tryptase, encompassing all forms, or mature tryptase, specifically targeting mature alpha and beta forms. Analyzing the total-to-mature ratio may offer insight into certain scenarios, although this assessment isn't internationally used or accessible.

Under normal circumstances, tryptase concentrations in the bloodstream remain minimal. However, when mast cells activate, these levels swiftly elevate, peaking within 15 to 30 minutes, and returning to baseline within several hours to a couple of days. In severe allergic reactions like anaphylaxis, characterized by low blood pressure, skin hives, airway constriction, and potentially fatal outcomes, elevated tryptase levels may manifest solely in cases associated with decreased blood pressure during the reaction. Interestingly, many food-related reactions might not exhibit elevated tryptase levels.

What do elevated tryptase levels mean?

Elevated tryptase levels in the blood can indicate several things, primarily related to mast cell activation. Here are a few reasons for elevated tryptase levels:

Anaphylaxis

During a severe allergic reaction, mast cells release tryptase into the bloodstream, causing an increase in its levels.

Mastocytosis

This is a condition where there's an abnormal accumulation of mast cells in the body. Elevated tryptase levels can be indicative of this condition.

Mast cell activation syndrome (MCAS)

This is a condition where mast cells are overly responsive and release excessive amounts of various substances, including tryptase, causing symptoms ranging from mild to severe.

Other conditions

Elevated tryptase levels can also be seen in certain cancers, autoimmune diseases, and inflammatory conditions, though it's less common.

If you've received results indicating elevated tryptase levels, it's essential to discuss these findings with a healthcare professional who can assess your symptoms and order further tests if needed to determine the underlying cause.

How does the Tryptase Blood Test work?

Consultation with a healthcare provider

The process usually begins with a consultation with a healthcare provider, who evaluates your symptoms, medical history, and any suspected allergic or anaphylactic reactions.

Order the test

Based on the assessment, the healthcare provider may order a tryptase blood test to measure the tryptase levels in your blood.

Preparation

Typically, no specific preparation is required for a tryptase blood test. However, it's essential to follow any instructions your healthcare provider provides, such as fasting or avoiding certain medications if necessary.

Blood sample collection

The actual test involves drawing a blood sample, usually from a vein in your arm. A healthcare professional will clean the area, tie an elastic band around your upper arm to increase blood flow, and insert a needle to draw the blood into a tube.

Labeling and sending the sample

The collected blood sample is then labeled with your information and sent to a laboratory for analysis. Proper labeling is crucial to ensure accurate results.

Laboratory Analysis

The blood sample is analyzed in the laboratory to measure the level of tryptase in the serum or plasma. This is often done using specialized tests and equipment.

Results

Once the analysis is complete, the results are sent back to your healthcare provider. The tryptase levels in your blood will be reported in nanograms per milliliter (ng/mL) or another appropriate unit.

Interpretation

Your healthcare provider will interpret the results in the context of your symptoms and medical history. Elevated levels may suggest conditions like anaphylaxis, mastocytosis, or mast cell activation syndrome, among others.

Further evaluation

Depending on the results and your clinical presentation, your healthcare provider may recommend further tests or procedures to determine the underlying cause if elevated tryptase levels are found.

Always discuss the results of any medical test with your healthcare provider, as they can provide context, explain what the results mean for your health, and guide you on any necessary next steps or treatments.

Clinical disorders or settings where the test may be helpful

Monitoring MCAS

For individuals diagnosed with mastocytosis or MCAS, regular monitoring of tryptase levels can help assess disease progression and response to treatment.

Allergy and immunology assessments

In some cases of chronic allergies or unexplained allergic-like symptoms, measuring tryptase levels might help identify mast cell involvement.

Evaluation of unexplained symptoms

If a patient presents with symptoms suggestive of systemic reactions, including skin reactions, gastrointestinal issues, or anaphylaxis-like episodes without a clear cause, tryptase testing might be considered as part of the investigation.

Post-mortem investigations

Tryptase levels can also be measured post-mortem in cases where anaphylaxis is suspected as a cause of death.

In these scenarios, a tryptase test serves as a diagnostic tool alongside other clinical assessments and tests. It's important to interpret the results in the context of the patient's medical history, symptoms, and other laboratory findings to make an accurate diagnosis and guide appropriate treatment.

The difference between tryptase testing and allergy blood testing

Tryptase testing and allergy blood testing serve different purposes and measure different substances in the blood.

Tryptase testing

• What it measures: Tryptase testing measures the level of tryptase, an enzyme released by mast cells when they're activated. Mast cells are a type of immune cell involved in allergic and inflammatory reactions.
• Clinical use: It's primarily used in diagnosing conditions related to mast cell activation, such as anaphylaxis, mastocytosis, and mast cell activation syndrome (MCAS).
• Procedure: Tryptase testing involves drawing a blood sample to measure the level of tryptase in the bloodstream. Elevated levels of tryptase can indicate mast cell activation.

Allergy blood testing

• What it measures: Allergy blood testing, such as specific IgE (immunoglobulin E) testing, measures the levels of antibodies (IgE) produced by the immune system in response to specific allergens, like pollen, pet dander, foods, or medications.
• Clinical use: It's used to identify specific allergies that may trigger allergic reactions in individuals.
• Procedure: Allergy blood testing involves drawing a blood sample and testing it against various allergens to determine if the body produces IgE antibodies against specific substances. Elevated IgE levels for certain allergens indicate an allergic response to those substances.

In summary, tryptase testing evaluates the activity of mast cells by measuring the level of tryptase they release, while allergy blood testing identifies specific allergens that trigger an allergic response by measuring IgE antibodies against those allergens. Both tests serve different diagnostic purposes in assessing allergic and immune reactions but target different components of the immune response.

CPT code information

The Current Procedural Terminology (CPT) code used for a tryptase test is typically CPT code 83520. This code specifically refers to the quantification of tryptase in blood.

However, it's important to note that CPT codes can vary based on the specific procedure performed, the laboratory, and any additional services or tests bundled with the tryptase measurement. Always verify the specific code used for billing purposes with the healthcare provider or laboratory conducting the test, as coding practices can vary over time and by location.

Research and evidence

Serum tryptase measurement post-allergic reactions remains underutilized, even following severe incidents of anaphylaxis. A sudden rise in serum tryptase signals mast cell degranulation, stemming from either an IgE-mediated process, as seen in penicillin allergies, or non-IgE pathways, such as with NSAIDs or opiates.

Tryptase levels elevate rapidly in the blood after anaphylaxis onset, peaking within minutes, then gradually returning to normal within 6–24 hours, correlating often with the severity of the episode (Centre UK, 2014).

Anaphylaxis presents as a severe, life-threatening systemic hypersensitivity reaction with swift-onset airway, breathing, and circulation issues (pharyngeal or laryngeal edema, bronchospasm, hypotension, or tachycardia), often accompanied by skin and mucosal changes (Centre UK, 2014).

However, certain symptoms resembling anaphylaxis could stem from other causes like acute cardiovascular or respiratory events. Timely serum tryptase measurement aids in distinguishing anaphylaxis as the cause, potentially reducing unnecessary investigations. An acute rise in serum tryptase also signifies the gravity of the reaction, prompting the identification of the triggering drug and related agents to mitigate future risks.

References

Centre (UK), N. C. G. (2014). Measuring serum tryptase after suspected anaphylaxis. In www.ncbi.nlm.nih.gov. National Institute for Health and Care Excellence (NICE). https://www.ncbi.nlm.nih.gov/books/NBK274147/#:~:text=The%20rise%20in%20tryptase%20levels

Labcorp. (n.d.). 004280: Tryptase | LabCorp. Www.labcorp.com. https://www.labcorp.com/tests/004280/tryptase

References

Centre (UK), N. C. G. (2014). Measuring serum tryptase after suspected anaphylaxis. In www.ncbi.nlm.nih.gov. National Institute for Health and Care Excellence (NICE). https://www.ncbi.nlm.nih.gov/books/NBK274147/#:~:text=The%20rise%20in%20tryptase%20levels

Labcorp. (n.d.). 004280: Tryptase | LabCorp. Www.labcorp.com. https://www.labcorp.com/tests/004280/tryptase