Serum/plasma concentration of histamine

What Is Histamine?

Histamine is a naturally occurring compound in your body that helps regulate immune responses, digestion, and blood flow. It’s released during allergic reactions, inflammation, or when certain cells (like mast cells) are activated. Your body breaks down histamine with enzymes, but when levels rise, it can cause symptoms like itching, swelling, or digestive upset.

Why Might You Need This Test?

Your doctor may order this test if you have symptoms like persistent itching, hives, digestive problems (e.g., nausea, diarrhea), or unexplained skin rashes. It can also help evaluate conditions like mastocytosis (a rare disorder where too many mast cells build up) or certain food intolerances.

How Is the Test Done?

A blood sample is taken from a vein in your arm. The sample is sent to a lab where it’s analyzed to measure histamine levels. Results are compared to general reference ranges, though individual needs may vary.

What Do Results Mean?

Elevated histamine levels may suggest an overactive immune response or mast cell disorder, while lower levels might indicate an enzyme deficiency (e.g., diamine oxidase). Your doctor will interpret results in the context of your symptoms and medical history.