D2.262 - Measurement of tryptasemia in a university hospital: prescribing reality versus recommendations

Tryptase reflects the number of copies of the alphatryptase gene, the number of mast cells present in the tissue and their state of activation. The test is therefore recommended for the diagnosis of anaphylaxis and for the screening, diagnosis and monitoring of mast cell disorders.

The aim was to evaluate whether tryptase testing is performed according to recommendations at the Grenoble Alpes University Hospital (GAUH).

We conducted a retrospective descriptive study of tryptases prescribed and tested in the GAUH laboratory between January and March 2022. For each test, we described the clinical situations that led to its prescription and assessed its relevance in the light of test recommendations.

We included 321 tests. The mean tryptasemia was 7.2 µg/dl ±8.4; 68% of the tests were within the prescription indication.

Of the total number of tests, 119 (37%) were performed in the context of anaphylaxis, either at the time of the reaction (26%) or during monitoring of basal tryptasemia (11%). In the acute setting, 57 tests (67%) met the recommendations. Deviation from recommendations was due to incorrect timing of prescription, with acute dosing more than 4 hours after onset of symptoms. In 21% of cases, the significant increase in tryptase was an argument for the diagnosis of anaphylaxis.

One hundred and seventy-four tryptase determinations (54%) were performed in the context of mast cell disorders, including 35 (21.1%) to screen for systemic mastocytosis, 15 (8.6%) for mast cell activation syndrome (MCAS), and the remainder for follow-up as recommended. Tryptasemia was prescribed outside guidelines 39 times (22.4%) for chronic urticaria (CU) and 24 times (13.8%) for abdominal pain without MCAS.

Our study showed that the majority of tests were performed according to the recommendations, but 19.6% of tests were ordered outside the consensus for CU or abdominal pain without MCAS. Moreover, more than 30% of tests in acute anaphylaxis situations were performed too late in relation to the onset of symptoms.