Description

A serotonin blood test measures the amount of serotonin in your blood: 

Purpose

• Order a serotonin blood test to help diagnose carcinoid tumors, which are slow-growing tumors that can form in the lungs or digestive tract. People with carcinoid syndrome often have high levels of serotonin in their blood. 

Preparation

• You should: Avoid eating foods high in serotonin, such as avocados, bananas, and grapefruit, for 48 hours before and during the test. 
• Stop taking medications that can increase serotonin levels, such as lithium, monoamine oxidase inhibitors, and selective serotonin reuptake inhibitors (SSRIs). 

Normal range

• The normal range for serotonin in the blood is 50 to 200 ng/mL (0.28 to 1.14 µmol/L). 

Serotonin is a chemical that helps transmit nerve impulses, constrict blood vessels, and affects mood. It's produced in the brain, bronchial tubes, and gastrointestinal tract. 

Fasting not required.