Histamine

This test measures histamine levels in your urine, a chemical released by immune cells during allergic reactions and inflammatory responses. Elevated urine histamine can indicate mast cell activation, allergic reactions, or certain tumors that produce excess histamine. This test helps diagnose conditions like mastocytosis or mast cell activation syndrome, which cause symptoms like flushing, itching, and gastrointestinal problems. It's typically collected as a 24-hour urine sample.