Mast Cell Tryptase (Serum or Plasma)

Why Is This Test Done?

Your healthcare provider may order this test to evaluate symptoms such as severe allergic reactions (e.g., anaphylaxis), chronic urticaria (hives), or mastocytosis—a rare disorder where too many mast cells build up in the body. It can also help monitor treatment responses in these conditions.

What Does the Result Mean?

Elevated tryptase levels may indicate recent or ongoing mast cell activation, which can occur with allergic reactions, certain cancers, or inflammatory diseases. However, results alone aren’t diagnostic—they’re often used alongside clinical findings and other tests.

Sample Collection and Preparation

A blood sample is drawn from a vein, usually in your arm. The sample is collected in a tube that separates serum (if clotted) or plasma (if anticoagulated). This test can be done on either, but plasma is sometimes preferred for stability.

What to Expect Before the Test

No special preparation is needed, but inform your provider about any medications (especially blood thinners) or recent illnesses that might affect results.