Serotonin
Serotonin is a neurotransmitter and hormone derived from the amino acid tryptophan. It plays a central role in regulating mood, sleep, appetite, digestion, temperature control, and vascular tone. While commonly associated with mental wellbeing, approximately 90% of the body’s serotonin is produced in the gastrointestinal tract, where it influences gut motility and function. Blood serotonin testing measures circulating levels and may provide insight into neuroendocrine activity, particularly in the context of suspected carcinoid tumours or certain gastrointestinal disorders. Because serotonin acts as both a neurotransmitter and peripheral signalling molecule, abnormal levels can reflect a range of physiological disturbances.
- Price: £155
- Code: SER
- TAT: 18 Working Days
- Sample Type: Blood
Clinical Significance
Elevated serotonin levels are most commonly associated with carcinoid tumours, a type of neuroendocrine tumour that may produce excess serotonin. Patients with carcinoid syndrome may experience flushing, diarrhoea, wheezing, and abdominal discomfort. In such cases, serotonin testing may be performed alongside 5-HIAA urine testing and chromogranin A measurement for comprehensive assessment. Low serotonin levels are more difficult to interpret in isolation. Although serotonin is widely linked to mood disorders, blood levels do not directly reflect central nervous system concentrations. Therefore, serotonin testing is not routinely used to diagnose depression or anxiety. In certain cases, serotonin measurement may assist in evaluating unexplained diarrhoea, suspected neuroendocrine activity, or rare metabolic disorders.
Who Might Benefit From This Test?
This test may be appropriate for individuals with symptoms suggestive of carcinoid syndrome, including flushing episodes, chronic diarrhoea, or unexplained wheezing. It may also be requested when neuroendocrine tumours are suspected based on imaging or clinical findings. Clinicians may include serotonin testing as part of a broader endocrine or oncological investigation where abnormal hormone production is suspected.
Sample Collection
A blood sample is collected by a trained healthcare professional in a clinical setting. The procedure is straightforward and completed within minutes. Samples are analysed in specialist laboratories to ensure accurate measurement.
Understanding Your Results
Results are interpreted in conjunction with clinical symptoms and additional investigations. Elevated levels may prompt further imaging studies or endocrine referral. Normal results reduce the likelihood of serotonin-producing tumours but may not fully exclude disease. Because interpretation depends heavily on clinical context, results are reviewed carefully to guide appropriate next steps.
FAQs
When will I receive my results?
Results are usually available within the stated turnaround time.
Should I discuss my results with a doctor?
Yes, results should always be reviewed with a qualified healthcare professional.
Why Choose Marylebone Diagnostic Centre?
Marylebone Diagnostic Centre provides comprehensive endocrine and neuroendocrine testing within a professional and discreet environment. With a turnaround time of 18 days, this test supports detailed evaluation of hormone-related conditions.
Book Now
Book the Serotonin (SER) test today to support thorough assessment of neuroendocrine function.
