Tryptase is a good indicator of the activation of mast cells, cells found in the tissues of the human body, present in greater quantity in the skin, the intestinal mucous membranes, the mucous membranes of the airways and the bone marrow.
Definition: What is tryptase?
Tryptase is a enzyme (protein) that is released along with histamine and other chemicals by mast cells. “This is a mediator of the allergic reaction : tryptase is secreted by mast cells, cells involved in allergic reactions“, notes Dr. Stéphanie Rogeau, immunologist.
When to do a tryptase assay?
The tryptase assay is prescribed by a doctor or an allergist as part of a suspected allergic reaction (redness, hives, swelling of the tongue, face and/or eyes, nausea, abdominal pain, asthma, hypotension, breathing difficulties, shock, etc.). Its interpretation will be made according to the basal tryptase, reference value in the patient, for the diagnosis of anaphylaxis. It can also help in the diagnosis of mastocytosis. It is in fact arare conditions associated with an abnormally high number of mast cells which accumulate in the skin or in several organs.
The tryptase assay is analyzed on serum in the laboratory from of a blood test. The first sample must be taken between 30 minutes to 2 hours after the event. The second at least 24 hours after the anaphylactic shock (basic tryptase). These two samples are essential to make the diagnosis because of the variations of basal tryptase in a patient. “The first tryptase assay performed at the time, against the background of allergic reactionusually in the emergency department, is important to allow proper interpretation compared to basal tryptase. The patient will be his own witness“, she specifies.
What is the normal level of a tryptase test?
The immunoenzymatic technique makes it possible to measure the different forms of alpha and beta tryptases (antibodies recognizing the two subunits). In a population of 124 healthy controls, the tryptase value is < 11 µg/ml for 95% of them. It’s about a reference value because there are great variations between individuals.
Do you have to be fasting?
The tryptase assay does not require fasting.
What does high tryptase mean?
Tryptase increases at the time of an anaphylactic event. If the tryptase level is elevated relative to the basal tryptase level at the time of an allergic reaction, this confirms anaphylaxis. A high basal tryptase dosage can be an argument for the diagnosis of mastocytosis. Additional tests will be needed to confirm this diagnosis.
Thanks to Dr Stéphanie Rogeau, Institute of Immunology, Center of Biology-Pathology-Medical Genetics of the University Hospital of Lille.