Serotonin (5-hydroxytryptamine, or 5-HT) is one of the body’s most important inhibitory neurotransmitters, involved in mood regulation, emotional stability, sleep, pain perception, digestion, and immune function. Although it is often called the “feel-good” neurotransmitter, serotonin’s role extends far beyond mental health — influencing nearly every system in the body.
In the central nervous system (CNS), serotonin promotes calmness, emotional balance, and healthy sleep–wake rhythms. In the peripheral system, about 90% of serotonin is produced in the gastrointestinal tract, where it supports gut motility, blood clotting, and immune signaling.
Serotonin is synthesized from the amino acid tryptophan, through two enzymatic steps:
Tryptophan → 5-HTP (5-hydroxytryptophan) via tryptophan hydroxylase (requires iron, oxygen, and tetrahydrobiopterin (BH4)).
5-HTP → Serotonin via aromatic L-amino acid decarboxylase (AADC) (requires vitamin B6).
Because serotonin synthesis depends on dietary tryptophan and key cofactors, any nutritional deficiency, inflammation, or stress-induced shift in metabolism can disrupt this pathway.
The Neurotransmitter XL panel provides a comprehensive view of serotonin metabolism alongside related neurotransmitters — dopamine, noradrenaline, adrenaline, GABA, and glutamate — as well as metabolic cofactors and pathways that influence serotonin production and breakdown.
Serotonin levels rarely change in isolation. They are closely linked to tryptophan metabolism and the kynurenine pathway, both of which are influenced by stress, inflammation, nutrient availability, and mitochondrial function. When chronic stress or immune activation diverts tryptophan toward the kynurenine pathway, serotonin synthesis decreases, which may contribute to low mood, anxiety, fatigue, or sleep disturbances.
This test helps clinicians evaluate not just serotonin itself, but also the metabolic context that determines its availability, conversion efficiency, and utilization.
Serotonin acts as a chemical messenger that helps regulate:
Mood and emotional balance – promotes feelings of calm, contentment, and optimism.
Sleep regulation – precursor to melatonin, the hormone that controls circadian rhythm and deep sleep.
Appetite and digestion – modulates gut motility and satiety signaling.
Pain perception – affects central pain modulation and sensitivity.
Cognitive function – influences focus, learning, and decision-making.
Stress adaptation – balances excitatory neurotransmitters (e.g., dopamine, noradrenaline) to prevent overstimulation.
A well-functioning serotonin system supports emotional stability, relaxation, and mental clarity — whereas imbalances can affect both mental and physical health.
Serotonin originates from tryptophan, an essential amino acid that can also be metabolized via the kynurenine pathway. Under normal conditions, a portion of tryptophan is used to make serotonin. However, under chronic stress, inflammation, or immune activation, the enzyme indoleamine 2,3-dioxygenase (IDO) becomes more active and diverts tryptophan toward kynurenine and its metabolites (such as quinolinic acid).
This process:
Reduces serotonin synthesis, contributing to low serotonin-related symptoms.
Increases neurotoxic metabolites, which can impair mitochondrial function and energy production.
Decreases NAD+ and ATP formation in the mitochondria, further affecting neuronal resilience.
By measuring serotonin along with tryptophan, kynurenine, quinolinic acid, NAD+, and relevant enzyme markers, the Neurotransmitter XL panel helps identify where serotonin production may be blocked or diverted.
Serotonin synthesis depends on:
Vitamin B6 – cofactor for converting 5-HTP to serotonin.
BH4 (tetrahydrobiopterin) – required for tryptophan hydroxylase activity.
Folate, B12, and niacin (B3) – maintain methylation and NAD+ pools critical for neurotransmitter synthesis.
Iron and magnesium – support enzymatic and redox processes.
Deficiencies in these nutrients can reduce serotonin formation or alter its balance with other neurotransmitters.
Chronic stress increases cortisol and catecholamine activity, shifting tryptophan metabolism away from serotonin toward kynurenine. Over time, this can produce serotonin depletion, mood instability, and sleep disruption.
Because most serotonin is synthesized in the gut, intestinal inflammation, dysbiosis, or malabsorption can reduce serotonin availability. Certain gut bacteria also produce or modulate serotonin precursors.
Excess alcohol, caffeine, or artificial sweeteners can inhibit serotonin synthesis or receptor activity. Sleep deprivation and chronic overstimulation can further impair serotonin metabolism.
Variations in tryptophan hydroxylase (TPH2) or serotonin transporter (SLC6A4) genes can influence serotonin synthesis, signaling, or reuptake efficiency.
| Related Marker | Interpretation Insight |
|---|---|
| Tryptophan | Low tryptophan with low serotonin suggests precursor deficiency or malabsorption. |
| Kynurenine / Quinolinic Acid | Elevated values indicate diversion of tryptophan metabolism away from serotonin synthesis. |
| NAD+ and Niacin Markers | Low NAD+ reduces mitochondrial energy and serotonin turnover efficiency. |
| BH4 and Vitamin B6 indicators | Deficiencies impair enzymatic conversion of tryptophan to serotonin. |
| Cofactors (Folate, B12, SAM) | Needed for methylation reactions and neurotransmitter balance. |
| Neopterin | Elevated levels suggest immune activation that may suppress serotonin synthesis via IDO activation. |
Together, these markers help distinguish whether low or high serotonin levels stem from nutrient deficiencies, inflammatory activation, mitochondrial dysfunction, or stress-related pathway shifts.
Depressed mood, sadness, or irritability
Anxiety, panic, or stress intolerance
Sleep difficulties (especially early awakening)
Carb cravings or appetite changes
Low pain threshold
Poor digestion or bowel irregularity
Although rare, elevated urinary serotonin can result from supplementation (e.g., 5-HTP or tryptophan), serotonergic medications (SSRIs, MAO inhibitors), or increased gastrointestinal production. It may also reflect slowed breakdown or increased peripheral turnover.
Interpretation requires caution — urinary serotonin reflects systemic, not central, activity and should always be viewed in metabolic context.
Chronic serotonin imbalance can lead to:
Mood instability and fatigue
Impaired sleep and circadian rhythm
Digestive changes and gut dysmotility
Reduced stress resilience
Diminished mitochondrial energy output
Correcting underlying nutrient, metabolic, and inflammatory imbalances can help restore proper serotonin function and emotional stability.
Enhance tryptophan intake: turkey, salmon, eggs, oats, seeds, and legumes.
Ensure adequate cofactors: vitamin B6, folate, B12, vitamin C, iron, and magnesium.
Reduce chronic stress: mindfulness, exercise, yoga, and consistent sleep schedules.
Support gut health: probiotic and prebiotic foods, address dysbiosis or inflammation.
Avoid serotonin-depleting habits: limit caffeine, alcohol, and artificial sweeteners.
Monitor medications: certain antidepressants or MAO inhibitors can alter serotonin metabolism — always consult a healthcare professional before combining supplements or medications.
Serotonin is a vital neurotransmitter that bridges emotional, cognitive, and physical health. On the Neurotransmitter XL panel, it provides deep insight into mood balance, stress response, mitochondrial health, and tryptophan metabolism. Because serotonin is influenced by diet, nutrient cofactors, inflammation, and the microbiome, its interpretation is most meaningful when viewed in the context of the entire biochemical network.
Import lab results from multiple providers, track changes over time, customize your reference ranges, and get clear explanations for each result. Everything is stored securely, exportable in one organized file, and shareable with your doctor—or anyone you choose.
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A decreased serotonin level on the Neurotransmitter XL panel suggests insufficient serotonin synthesis, accelerated breakdown, or diversion of its precursor tryptophan into other metabolic pathways, such as the kynurenine pathway. Because serotonin influences mood, sleep, digestion, pain perception, and stress resilience, low levels often manifest as emotional, cognitive, and physical fatigue.
Unlike many neurotransmitters that stimulate activity, serotonin acts as a calming and stabilizing messenger—balancing the excitatory effects of dopamine and noradrenaline. When serotonin becomes depleted, this regulatory balance is lost, often leading to irritability, anxiety, insomnia, and low mood.
Serotonin is synthesized from the amino acid tryptophan, which must be obtained through the diet.
Low protein intake, restrictive diets, gut inflammation, or malabsorption can limit tryptophan availability.
Because tryptophan shares transporters with other amino acids, high-protein meals can also reduce its entry into the brain.
Serotonin synthesis relies on several vitamins and cofactors:
Vitamin B6 – required to convert 5-HTP into serotonin.
BH4 (Tetrahydrobiopterin) – necessary for tryptophan hydroxylase activity.
Folate, Vitamin B12, and Niacin (B3) – maintain methylation balance and NAD+ for neurotransmitter production.
Iron and Magnesium – support enzymatic and redox reactions essential to serotonin metabolism.
Deficiencies in these nutrients can significantly slow serotonin formation.
Prolonged stress increases cortisol and catecholamine output, activating indoleamine 2,3-dioxygenase (IDO)—an enzyme that diverts tryptophan away from serotonin synthesis and into the kynurenine pathway.
This shift results in:
Lower serotonin levels
Accumulation of neurotoxic kynurenine metabolites (e.g., quinolinic acid)
Decreased mitochondrial NAD+ and ATP production
Over time, this contributes to emotional exhaustion, reduced energy, and burnout.
Since most serotonin is produced in the intestinal tract, gut inflammation, dysbiosis, or leaky gut can interfere with production and signaling.
Certain beneficial bacteria (e.g., Bifidobacteria, Lactobacillus) promote serotonin synthesis; when they are depleted, serotonin output may decline.
Systemic inflammation activates the kynurenine pathway via cytokine signaling (especially interferon-γ), redirecting tryptophan from serotonin toward immune-modulating metabolites.
Elevated neopterin levels on the panel often indicate this immune-driven tryptophan diversion.
Low NAD+ or oxidative stress can limit serotonin turnover and recycling. Mitochondrial inefficiency reduces the availability of ATP needed for neurotransmitter synthesis, compounding fatigue and mood instability.
Chronic alcohol use, excessive caffeine, and certain drugs (e.g., steroids, stimulant medications) may suppress serotonin synthesis or receptor sensitivity.
Insufficient sleep, overtraining, and lack of sunlight can also reduce serotonin and melatonin production.
Low serotonin affects multiple systems. Common symptoms include:
Depressed mood or emotional flatness
Anxiety or panic episodes
Sleep difficulties (especially early morning awakening)
Fatigue and poor stress tolerance
Carbohydrate cravings or appetite changes
Low motivation and mental fog
Digestive irregularities (constipation or sluggish motility)
Increased pain sensitivity
Because serotonin interacts with the gut-brain axis, individuals may experience both psychological and gastrointestinal symptoms.
| Related Marker | Interpretation Insight |
|---|---|
| Tryptophan | Low tryptophan with low serotonin suggests limited precursor availability or malabsorption. |
| Kynurenine / Quinolinic Acid | Elevated values indicate immune-driven diversion of tryptophan metabolism. |
| BH4 and B6 Indicators (Cystathionine, NAD+) | Low values reflect cofactor insufficiency impairing serotonin synthesis. |
| Neopterin | High levels suggest inflammation-induced IDO activation suppressing serotonin. |
| SAM / SAH Ratio | Low ratio may indicate poor methylation, affecting neurotransmitter balance and melatonin conversion. |
| Lactate / Pyruvate | Abnormalities point to mitochondrial energy constraints affecting serotonin turnover. |
Together, these insights help determine whether serotonin depletion stems from precursor limitation, inflammation, nutrient deficiencies, or energy metabolism issues.
Persistently low serotonin can contribute to:
Depression, anxiety, and mood instability
Chronic fatigue or burnout
Sleep cycle disruption and poor recovery
Gastrointestinal dysfunction
Impaired cognitive performance and memory
Low stress resilience and immune dysregulation
Addressing serotonin deficiency early can support both mental and physical restoration.
Enhance dietary tryptophan intake: turkey, eggs, fish, tofu, oats, nuts, and seeds.
Replete essential cofactors: vitamin B6, B12, folate, niacin, iron, and magnesium.
Reduce chronic stress: mindfulness, breathwork, restorative exercise, and sufficient sleep.
Support gut health: probiotic and prebiotic foods, manage inflammation or malabsorption.
Light exposure and movement: morning sunlight and regular physical activity support serotonin and melatonin balance.
Avoid inhibitory substances: limit alcohol, caffeine, and artificial sweeteners that disrupt serotonin pathways.
Supplementation with tryptophan or 5-HTP may help increase serotonin levels but should only be used under medical supervision, especially if you are taking serotonergic medications (e.g., SSRIs or MAO inhibitors).
Low serotonin reflects a disruption in the body’s ability to synthesize or sustain this critical neurotransmitter. It often results from stress, nutrient deficiencies, inflammation, or gut dysfunction, leading to symptoms that affect both mood and energy.
On the Neurotransmitter XL panel, serotonin levels are best understood in the context of tryptophan metabolism, immune activation (neopterin), methylation capacity (SAM/SAH), and mitochondrial function.
Laboratories
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Designed for professionals managing their clients' lab reports
About membership
Import Lab Results from Any Source
Easily upload lab results from any provider, whether it's a hospital, independent lab, or home testing service. We support PDFs, scanned documents, and JPEGs from patient portals. No need to log in to multiple platforms — everything is centralized in one secure space.
Easily upload lab results from any provider — we support PDFs, scans, and images. Keep all your reports organized in one secure place.
See Your Health Timeline
Every lab result is automatically organized on a chronological timeline, giving you a complete picture of your health journey. Whether you're tracking a condition, managing treatments, or staying proactive, the timeline helps you and your doctor understand how things progress over time.
Every lab result is automatically organized on a chronological timeline, giving you a complete picture of your health journey.
Understand What Your Results Mean
Whether it's a blood test, GI panel, urinalysis, or something else, lab reports measure numerous biomarkers that reveal what's happening inside your body. Our extensive database covers over 10,000 biomarkers, providing clear, simple explanations of what each result means and how you can take action—no matter your membership level. Say goodbye to confusion and get the insights you need to better understand your health.
Our database covers over 10,000 biomarkers with clear, simple explanations—so you can finally understand your results and what to do next.
Enter Your Lab Reports Yourself — Always Free
Enter Your Lab Reports — Always Free
If you'd like to handle inputting your health data into your account, you can do so with our easy-to-use data entry forms. Our user-friendly form is designed to guide you through the quick and easy submission process, making it simple to keep track of your health metrics. This is available to both Complete plan and Unlimited plan members.
Our user-friendly form guides you through a quick, simple submission process, making it easy to enter your health metrics.
Add your results anytime with our easy entry form. It's quick, guided, and helps you stay organized — free for all members.
Visualize Your Results
View your lab data through easy-to-read graphs and tables. Quickly spot patterns, track changes, and compare results across different dates — all without digging through multiple reports. You can also select and compare graphs of specific biomarkers side-by-side to better understand how they relate and change over time.
See your lab reports in clear graphs and tables. Spot patterns, track changes, and compare results over time — all in one place.
Export Your Complete Lab History in a Single File
Export Your Complete Lab History
After collecting lab results from different providers, you can download your entire history combined into a single file. Choose from PDF, Excel, or CSV formats to easily review, share, or get a second opinion—no more juggling multiple reports.
After collecting lab results from different providers, you can download your entire history combined into a single file.
Comprehensive Data Entry Service for Your Reports
Data Entry Service for Your Reports
Our inclusive service handles the data entry for your lab reports. Just submit your information and we'll take care of the rest. Complete plan members receive one report entered for free, then $15 per report after that. Unlimited plan members receive ten report entries for free, then $15 per report after that.
Our inclusive service handles the data entry for your lab reports. Just submit your information and we'll take care of the rest.
Securely Share With Anyone You Trust
Whether you're working with a doctor, nutritionist, caregiver, or wellness coach, you can securely share your complete lab history by sending an invite link to anyone you trust. You have full control over who sees your information and for how long, ensuring your privacy and peace of mind at every step.
Share your full lab history with your doctor, nutritionist, or coach using a secure invite link.
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I have been using Healthmatters.io since 2021. I travel all over the world and use different doctors and health facilities. This site has allowed me to consolidate all my various test results over 14 years in one place. And every doctor that I show this to has been impressed. Because with any health professional I talk to, I can pull up historical results in seconds. It is invaluable. Even going back to the same doctor, they usually do not have the historical results from their facility in a graph format. That has been very helpful.
Anthony
Unlimited Plan Member since 2021
What fantastic service and great, easy-to-follow layouts! I love your website; it makes it so helpful to see patterns in my health data. It's truly a pleasure to use. I only wish the NHS was as organized and quick as Healthmatters.io. You've set a new standard for health tracking!
Karin
Advanced Plan Member since 2020
As a PRO member and medical practitioner, Healthmatters.io has been an invaluable tool for tracking my clients' data. The layout is intuitive, making it easy to monitor trends and spot patterns over time. The ability to customize reports and charts helps me present information clearly to my clients, improving communication and outcomes. It's streamlined my workflow, saving me time and providing insights at a glance. Highly recommended for any practitioner looking for a comprehensive and user-friendly solution to track patient labs!
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Healthmatters Pro Member since 2024
Healthmatters is a personal health dashboard that helps you organize and understand your lab results. It collects and displays your medical test data from any lab in one secure, easy-to-use platform.
With a Healthmatters account, you can:
Professionals can also analyze client data more efficiently and save time managing lab reports.
Healthmatters.io personal account provides in-depth research on 4000+ biomarkers, including information and suggestions for test panels such as, but not limited to:
You can combine all test reports inside your Healthmatters account and keep them in one place. It gives you an excellent overview of all your health data. Once you retest, you can add new results and compare them.
If you are still determining whether Healthmatters support your lab results, the rule is that if you can test it, you can upload it to Healthmatters.
While we work with many popular labs, we welcome reports from lots of other places too.
It's as simple as this: if you can get a test done, you can upload it to Healthmatters and we can interpret results from any lab out there. If laboratories can analyze it, we can interpret it.
If you're on the hunt for a specific biomarker, contact us and we'll add it to our database. Anything from blood, urine, saliva, or stool can be uploaded, understood, and tracked with your Healthmatters account.
The Complete Plan ($15/month) is perfect for individuals who want ongoing access to their health data. It includes unlimited lab imports, visual tracking, custom ranges, result explanations, full account exports, and secure sharing — all with a simple monthly subscription. You can cancel anytime and restart your plan whenever you're ready — your data will still be there waiting for you. You can also upgrade to the Unlimited Plan at any time, with the cost prorated based on what you've already paid.
The Unlimited Plan ($250 one-time) is also designed for individuals but offers lifetime access with no ongoing subscription. You'll get all the same features as the Complete Plan, plus a larger initial data entry allowance (10 reports), making it a great choice if you prefer a one-time payment and long-term use without monthly fees.
In short:
There are two ways to add your test reports to your Healthmatters account. One option is to input the data using the data entry forms. The other method is to utilize our "Data entry service."
Our data entry forms offer an easy, fast, and free way for you to input the reports yourself. Self-entry allows you to add an unlimited number of reports at no cost. We make the self-entry process user-friendly, providing dozens of templates that pre-populate the most popular laboratory panels and offering instant feedback on entered values.
For those who prefer assistance, we offer a "Data entry service" to help you input your data. Simply attach an image or file of your lab test results, and a qualified team member from our data entry team will add the results for you.
We support various file types, including PDFs, JPGs, or Excel. This service is particularly useful if you have many reports to upload or if you're too busy to handle the data entry yourself.
Our Data Entry Service is for when you don't want to manually type in your lab results yourself. You simply upload your report (PDF, image, or screenshot), and our trained team enters the information into your Healthmatters account for you — accurately and neatly organized, ready to view in graphs, tables, and timelines.
The $15 per report covers the time and care it takes for a real person to review your file, make sure each result is entered correctly, and double-check for accuracy. This ensures your health data is precise and easy to work with — without you having to spend the time doing it yourself.
Prefer to do it yourself? You can always use our free self-entry tool to add results manually — it just takes a bit more time and attention.
For users on the Complete monthly plan, the first report is entered free of charge, and each additional report incurs a fee of $15.
Unlimited account holders enjoy the entry of ten reports without charge. Subsequent reports are subject to a $15 fee per report.
Additionally, users on the Complete plan can upgrade to a yearly subscription from the account settings. The annual subscription includes a data entry service for five reports.
All professional accounts allow you to import and onboard an unlimited number of clients and their lab results. The distinction between professional plans lies solely in the data entry service.
The Pro Monthly Plus plan is priced at $75 per month and includes a data entry service for five reports each month. Additional reports can be self-entered at no extra cost or, if preferred, you can use our data entry service for an additional fee of $15 per report.
The Pro Monthly plan is priced at $45 per month and does not include a data entry service. Self-entry is free for an unlimited number of reports, and you can opt for the data entry service at a fee of $15 per report.
You also have the option to upgrade to higher monthly or to annual plans, which come with substantial discounts. All upgrades can be done directly from your account.
Simply log in and navigate to your account settings to cancel your subscription. Scroll down to locate the 'Cancel' button at the bottom of the page. Ensure you cancel at least one day before the renewal date to prevent any charges. Once cancellation is requested, the subscription remains active until the conclusion of the current billing cycle.
Our goal has been to make your Healthmatters account as intuitive as possible.
We've crafted multiple ways for you to navigate your data, whether you're glancing at a single report or delving into your historical test reports.
1. Graph View:Dive into a visual journey with our biomarker graphs, showcasing over 40 data points. Combining years of results unveils trends, empowering you to make informed decisions. Our visualization tools make it a breeze to compare and understand changes over time, even if your results are from different labs. A search function and filters simplify the exploration of extensive data, allowing you to focus on what needs attention.
2. All Tests ViewExplore neatly organized reports on a timeline, highlighting crucial details like dates, critical results, and lab/panel names. Each report opens up to reveal in-depth descriptions and additional recommendations for each biomarker. The history of previous results is just a click away, and you can download a comprehensive report for deeper insights. Color-coded and user-friendly, it's designed for easy reading, understanding, and navigation.
3. Table View:For a holistic view of all biomarkers side by side, our table view is your go-to. Results are neatly displayed in a categorized and dated table, ideal for those with an extensive test history. Utilize sorting, filters, and color-coding to enhance your analysis and gain extra insights.
Yes, you can download your information anytime. We offer two easy ways to export your lab data:
This makes it simple to save, back up, or share your health data whenever you need.
Yes, you can print your report. To do so, navigate to "All tests" and open the report you wish to print. You'll find a print button in the right corner of the report. Click on it, and your browser's print window will open. If you prefer to print in a bigger typeface, adjust the scale using the print window settings.
Yes, you can! We highly recommend activating Two-Factor Authentication (2FA) for your account. To do so, please navigate to the "Profile and Security" section of your account, where you will find instructions for activating 2FA.
Yes, you can. When entering values for the biomarker, you will see an "Edit Range" button. Click this button, and you'll have the option to enter a custom range.
A personal account is all about keeping your own lab test results in check. It's just for you and your personal use.
The professional account is designed for health professionals who wish to track and organize their clients' laboratory results.
To learn more about Healthmatters Pro, please refer to the professional page.
At HealthMatters, we're committed to maintaining the security and confidentiality of your personal information. We've put industry-leading security standards in place to help protect against the loss, misuse, or alteration of the information under our control. We use procedural, physical, and electronic security methods designed to prevent unauthorized people from getting access to this information. Our internal code of conduct adds additional privacy protection. All data is backed up multiple times a day and encrypted using SSL certificates. See our Privacy Policy for more details.
Optimal Result:
80 - 190 µg/g Crea.