What does the Tryptase, Serum (Total — Alpha and Beta) test measure?

Why is Tryptase, Serum (Total — Alpha and Beta) measured?

Serum tryptase serves two distinct and temporally separated clinical roles that are determined by when the specimen is collected relative to any acute mast cell activation event. Acute tryptase measurement — collected 30–120 minutes following a suspected anaphylactic or severe allergic reaction — confirms mast cell degranulation as the mechanism of the acute event, with a rise above the individual's personal baseline meeting diagnostic criteria for anaphylaxis per WAO and AAAAI guidelines. The validated formula for a diagnostically significant acute rise is: peak tryptase ≥ 1.2 × (individual baseline tryptase) + 2 ng/mL. Baseline tryptase measurement — collected at least 24 hours after any acute event in a clinically stable patient — quantifies the constitutive mast cell burden and is the primary diagnostic and monitoring marker for systemic mastocytosis, mast cell activation syndrome (MCAS), and hereditary alpha-tryptasaemia (HAT). A baseline tryptase persistently above 20 ng/mL is a WHO major diagnostic criterion for systemic mastocytosis, requiring bone marrow biopsy for confirmation. Elevated baseline tryptase in the 11.4–20 ng/mL range requires contextualisation with clinical features to distinguish early or indolent systemic mastocytosis, MCAS, hereditary alpha-tryptasaemia, chronic kidney disease, or myeloid malignancy as the underlying cause.

Reference ranges

Standard reference

<11.4 ng/mL (baseline/resting) # REVIEWER FLAG: Confirm Quest Diagnostics reference range for total serum tryptase — the 11.4 ng/mL upper limit of normal is the established threshold used across most reference laboratory platforms and is aligned with WHO systemic mastocytosis criteria; confirm Quest's specific threshold and whether they apply the same 11.4 ng/mL cut-off or a platform-specific value. Confirm assay methodology — ImmunoCAP fluorescent enzyme immunoassay (Thermo Fisher) is the dominant clinical platform; confirm whether Quest uses this or an alternative assay, as cross-platform comparability is limited.

Functional medicine optimal

Baseline tryptase: <5 ng/mL (functional medicine minimal mast cell activation burden target; levels approaching or above 8 ng/mL warrant clinical evaluation for hereditary alpha-tryptasaemia or indolent mast cell disease even within the reference range). # REVIEWER FLAG: The <5 ng/mL functional optimal is based on emerging HAT literature suggesting that baseline tryptase above 8 ng/mL may indicate TPSAB1 gene duplication even within the reference range — reviewer to confirm appropriate framing and whether this threshold should be cited with HAT-specific context.

Units

ng/mL, µg/L

Reference ranges vary by laboratory and assay platform. Interpret in context of the issuing laboratory's stated range.