What it measures
Whether something in a person's serum makes immune cells release histamine. The lab mixes the serum with blood cells from a donor and measures the histamine those cells release, as a percentage. A high release points to autoantibodies that set the cells off directly.
Why people test it
- Investigating chronic hives (urticaria) that keep coming back over weeks or months.
- Checking whether chronic hives have an autoimmune cause.
Typical range
The result is a percentage compared with the lab's cut-off. Cut-offs vary by lab and method, and your report shows the lab's own cut-off and how it reads the result.
Finger-prick or vein?
Providers offer this test only from a vein sample, taken at a clinic or by a visiting nurse.