Acute Tryptase Rise (mast cell activation)

What the result means

The rule

An acute tryptase above 1.2 times the baseline plus 2 ng/mL supports mast cell activation.

What it is not

A threshold. It is a rise from that person’s own baseline, so an acute value inside the laboratory reference range can meet it and one above that range can fail it.

The timing

Acute sample about thirty minutes to four hours after the reaction; baseline at least twenty-four hours after everything has settled. A baseline drawn too early is not a baseline.

A tryptase that does not rise

Does not exclude anaphylaxis. It frequently fails to rise in food-triggered reactions, and anaphylaxis is a clinical diagnosis never withheld pending a level.

A raised baseline

Above 20 ng/mL is a minor criterion for systemic mastocytosis, and a separate question from this rise. Hereditary alpha-tryptasemia raises it too.

One value alone

Answers nothing. Without a baseline there is no rule to apply.