I had a 5-hiaa 24 hr. urine. the result was 2.5, normal is stated on the result from the lab is <=8.0, what does this mean?

Not carcinoid tumor: 5-hiaa is a urine test that reflects a chemical released from an endocrine type cell in a specific tumor originating in the nerve tissue called "carcinoid" tumor, and has many symptoms, including flushing, wheezing, diarrhea and abdominal pain. It can cause significant heart problems as well. A negative test suggests this tumor is not present.

Serotonin : It means that you do not have a serotonin producing tumor. It doesn't exclude other tumors. Wish you good health.