Serotonin, a chemical produced in your brain, is essential for life. Your brain and nerve cells depend on serotonin for normal function. The chemical also is related to mood. Many clinically depressed people take medications that boost serotonin levels. Sometimes the body makes too much serotonin, as with carcinoid tumour sufferers. Serotonin levels can be checked through blood and urine tests.
Ask your doctor if you should stop taking any of your regular medications before testing your serotonin levels. Over-the-counter cough medicines, ginseng, St. John's wort, antidepressants and other medications can affect serotonin levels, according to the Mayo Clinic.
Have a blood sample drawn. A lab will measure your levels and notify your doctor of irregularities. Normal levels of serotonin range from 101 to 283 nanograms per millilitre (ng/ml), according to the National Institutes of Health.
Participate in a 24-hour urine collection test to measure 5-HIAA acid, a breakdown product of serotonin. People with carcinoid tumours and higher than normal serotonin levels also often have high 5-HIAA levels. For 72 hours prior to your testing date, avoid eating foods that can affect the test results. The American Association for Clinical Chemistry states that avocadoes, eggplant, kiwi, bananas, plums, pineapples, walnuts and tomatoes can alter serotonin and 5-HIAA levels.