Surreal illustration of neural pathways and serotonin molecules in a human head, symbolizing head and neck paragangliomas.

Unlocking the Mystery of Head and Neck Paragangliomas: What You Need to Know About Serotonin and Diagnosis

Theo Raines in Health & Wellness August 2025 • 4 min read.

"New research sheds light on the role of serotonin in head and neck paragangliomas, offering insights for better diagnosis and management."

Head and neck paragangliomas (HNPGLs) are rare tumors that develop in specialized nerve tissue. These tumors, while uncommon, can sometimes produce hormones like catecholamines, leading to a variety of symptoms. Researchers have also noted that HNPGLs can exhibit characteristics similar to carcinoid tumors, which are known to produce serotonin. This raises questions about whether HNPGLs might also secrete serotonin, and if so, whether measuring serotonin levels could be useful in diagnosis or management.

Serotonin, once produced, is broken down into 5-hydroxyindoleacetic acid (5-HIAA), which is then excreted in urine. Doctors often measure urinary 5-HIAA levels to detect carcinoid tumors. Given the similarities between HNPGLs and carcinoid tumors, scientists have investigated whether measuring 5-HIAA in urine could also help in the diagnosis or management of HNPGLs. However, the connection between serotonin production and HNPGLs remains an area of active research.

A new study has explored the question of serotonin production in HNPGLs. The study aimed to determine whether urinary 5-HIAA levels are elevated in patients with HNPGLs, and whether measuring these levels could provide valuable clinical information. This research helps clarify the role of serotonin in HNPGLs and informs clinical practices for diagnosing and managing these rare tumors.

The Study: Investigating Serotonin Levels in HNPGL Patients

Surreal illustration of neural pathways and serotonin molecules in a human head, symbolizing head and neck paragangliomas.

Researchers conducted a study involving 114 patients diagnosed with HNPGLs. The study involved collecting two 24-hour urine samples from each participant to measure the levels of 5-HIAA, as well as various catecholamines and their metabolites. The goal was to determine if 5-HIAA levels were consistently elevated in these patients, which would suggest that HNPGLs commonly produce serotonin.

The study defined an increased excretion rate as any hormone level exceeding the average reference range derived from two urine samples. To ensure accuracy, patients with excessive catecholamine levels underwent additional imaging tests, such as 123I-MIBG scintigraphy, MRI, and CT scans, to rule out other paragangliomas in the chest or abdomen. Genetic testing was also performed to check for mutations in genes related to succinate dehydrogenase (SDH), a known factor in HNPGL development.

Key aspects of the study included:

Measurement of 5-HIAA and catecholamine levels in urine samples.
Exclusion of other tumor locations through imaging.
Genetic screening for SDH mutations.
Strict dietary guidelines for urine collection.

The results showed that the mean urinary 5-HIAA excretion rate was 14±9 µmol/24 hours, within the normal reference range of 10-44 µmol/24 hours. Only one patient had a slightly elevated 5-HIAA level (48 µmol/24 hours), but this patient had normal catecholamine levels. Notably, none of the 50 patients with elevated catecholamines or their metabolites showed elevated 5-HIAA excretion. These findings suggest that increased serotonin production is not a common feature of HNPGLs.

Clinical Implications: Reassuring News for HNPGL Patients

The study's conclusion offers valuable insights for the clinical management of HNPGLs. Since urinary 5-HIAA excretion is generally within the normal range in most HNPGL patients, routine measurement of 5-HIAA levels may not be necessary. The researchers emphasized that the assessment of urinary 5-HIAA excretion rates adds no additional value to the combination of radiological and routine biochemical assessment of these patients, especially compared to routine radiological and biochemical assessments. This can help doctors avoid unnecessary testing and focus on more relevant diagnostic measures.

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This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.5301/jbm.2012.9312, Alternate LINK

Title: Urinary 5-Hiaa Excretion Is Not Increased In Patients With Head And Neck Paragangliomas

Subject: Cancer Research

Journal: The International Journal of Biological Markers

Publisher: SAGE Publications

Authors: Leonie T. Van Hulsteijn, Nicolette Van Duinen, Johannes A. Romijn, Johannes W.A. Smit, Eleonora P.M. Corssmit

Published: 2012-04-01

Everything You Need To Know

What are head and neck paragangliomas (HNPGLs) and why was serotonin production suspected in these tumors?

Head and neck paragangliomas (HNPGLs) are rare tumors that develop in specialized nerve tissue. While uncommon, they can sometimes produce hormones like catecholamines, leading to various symptoms. Researchers have observed similarities between HNPGLs and carcinoid tumors, which are known to produce serotonin. This led to investigating whether HNPGLs might also secrete serotonin and if measuring serotonin levels could aid in diagnosis or management. Further research is still being conducted in this area.

How did the researchers conduct the study to investigate serotonin levels in patients diagnosed with HNPGL?

The study involved collecting two 24-hour urine samples from 114 patients diagnosed with HNPGLs to measure levels of 5-HIAA (a serotonin breakdown product), catecholamines, and their metabolites. Researchers aimed to determine if 5-HIAA levels were consistently elevated, suggesting HNPGLs commonly produce serotonin. The study also excluded other tumor locations through imaging, performed genetic screening for SDH mutations, and implemented strict dietary guidelines for urine collection to ensure accuracy.

What were the main findings regarding serotonin levels (measured as 5-HIAA) in HNPGL patients based on the study?

The study revealed that urinary 5-HIAA excretion was generally within the normal reference range in most HNPGL patients. Only one patient had slightly elevated 5-HIAA levels, but this patient had normal catecholamine levels. None of the patients with elevated catecholamines or their metabolites showed elevated 5-HIAA excretion. These findings suggest that increased serotonin production is not a common characteristic of HNPGLs.

What are the clinical implications of the study's findings for managing HNPGL patients, particularly regarding the necessity of routine serotonin level measurements?

The research suggests that routine measurement of 5-HIAA levels may not be necessary for most HNPGL patients. The assessment of urinary 5-HIAA excretion rates adds no additional value to the combination of radiological and routine biochemical assessment of these patients. Clinicians can avoid unnecessary testing and focus on more relevant diagnostic measures.

Why was genetic testing for succinate dehydrogenase (SDH) mutations performed in the study, and what are the implications of these mutations in HNPGL development?

Succinate dehydrogenase (SDH) mutations are a known factor in HNPGL development. Genetic testing was conducted in the study to check for these mutations in the participants. SDH is an enzyme complex that plays a crucial role in the citric acid cycle and mitochondrial respiration. Mutations in genes related to SDH can disrupt cellular metabolism and contribute to tumor formation in HNPGLs. Identifying these mutations can have implications for understanding the genetic basis of HNPGLs and potential targeted therapies.