Neurotransmitter XL
Performed by: getTested
A comprehensive map of stress biology, neurotransmitters, and tryptophan metabolism
Neurotransmitter XL is a broad, functional assessment of the brain–body chemical messengers that shape mood, focus, sleep, energy, and resilience to stress. The panel investigates more than 30 biomarkers that span classic neurotransmitters (dopamine, noradrenaline, adrenaline, serotonin), inhibitory/excitatory balance (GABA and glutamate), the tryptophan–kynurenine pathway, catecholamine metabolism, key enzyme activities, essential cofactors (B vitamins, SAM, BH4), and objective markers linked to mitochondrial function and nitrosative stress.
Modern life exposes many people to persistent stressors—performance pressure, family or relationship challenges, uncertainty around work or finances. These factors engage neuroendocrine stress axes that raise cortisol and catecholamines. Over time, chronic stress can deplete neurotransmitters and strain cellular energy production, contributing to low mood, fatigue, sleep disruption, brain fog, and “burnout.” The Neurotransmitter XL panel is designed to identify such stress-related shifts early and to illuminate targeted, evidence-informed next steps with your clinician.
What this test measures
Core neurotransmitters
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Dopamine, Noradrenaline (Norepinephrine), Adrenaline (Epinephrine)
Synthesized from tyrosine via L-DOPA, these catecholamines influence attention, motivation, cardiovascular tone, and the acute stress response. The panel also evaluates how efficiently these signals are inactivated (e.g., via COMT and MAO), offering context for sustained stress arousal patterns. -
Serotonin
An inhibitory neurotransmitter derived from tryptophan that supports mood stability, calm, sleep, and gut function; it also serves as a precursor to melatonin. -
GABA and Glutamate
GABA is the primary inhibitory neurotransmitter; glutamate is the primary excitatory neurotransmitter. Their balance is central to mental clarity, learning, emotional steadiness, and stress modulation.
Tryptophan and the kynurenine pathway
The panel goes beyond serotonin to assess tryptophan metabolism end-to-end. Under inflammatory or stress conditions, tryptophan is increasingly shunted from serotonin production toward kynurenine and downstream metabolites (e.g., quinolinic acid). This shift can:
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Reduce serotonin availability (with possible effects on mood and sleep).
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Increase neurotoxic and pro-oxidative compounds.
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Impair cellular energy by lowering NAD generation, with downstream effects on mitochondrial ATP output.
By profiling kynurenine-pathway activity and related enzymes (e.g., IDO, KMO), the test clarifies whether stress and immune activation are redirecting tryptophan away from serotonin.
Catecholamine metabolism and enzyme context
Patterns in catecholamines are interpreted alongside enzyme-related breakdown routes (COMT → metanephrines; MAO → VMA). Persistently elevated values after lifestyle factors are addressed may prompt clinicians to consider enzyme capacity or genetic variants (e.g., COMT polymorphisms) that can slow clearance.
Cofactors that enable healthy neurotransmission
Neurotransmitter synthesis and breakdown require adequate cofactors:
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B-vitamins: B6 (pyridoxal-5-phosphate), B12, folate;
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Vitamin C, magnesium, and copper in specific steps;
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Niacin (Vitamin B3) / NAD status for energy metabolism and pathway regulation;
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SAM (S-adenosyl-methionine) for methylation-dependent reactions;
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BH4 (tetrahydrobiopterin) as a critical cofactor in serotonin and catecholamine synthesis.
Where appropriate, the panel uses functional markers (e.g., methylmalonic acid for B12; cystathionine for B6 sufficiency; NAD and niacin species) to help identify bottlenecks that can block synthesis or skew pathways.
Mitochondrial and nitrosative stress markers
Because stress biology intersects with cellular energy, the profile includes organic acids and related indicators that can hint at:
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Reduced pyruvate flux into the TCA cycle or compensatory lactate build-up;
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Beta-oxidation constraints or L-carnitine insufficiency (e.g., suberic acid patterns);
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Nitrosative stress signatures (e.g., citrulline with mitochondrial context like citrate).
These data help differentiate “neurotransmitter depletion” from mitochondrial-driven low energy, which may feel similar but arise from different root causes.
Immune activation and gut-derived signals
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Neopterin can reflect TH1-type immune activation (e.g., IFN-γ-linked states) that often upregulate IDO/KMO, pushing tryptophan away from serotonin.
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TMAO context connects dietary precursors (choline, betaine, L-carnitine), microbiome activity, inflammation risk, and the need to avoid over- or under-supplying key nutrients that are also essential for neurotransmission and membrane integrity.
Why this matters
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Chronic stress re-wires biochemistry. Long-standing anxiety and overload can deplete neurotransmitters, alter tryptophan fate, and suppress mitochondrial ATP output, driving exhaustion.
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Symptoms overlap but causes differ. Low mood, poor sleep, and fatigue can stem from neurotransmitter deficits, impaired methylation, micronutrient shortfalls, immune activation, or mitochondrial bottlenecks.
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Actionable patterns. By pairing neurotransmitters with pathway enzymes, cofactors, and energy markers, clinicians can design targeted, staged care plans that address the right leverage points.
Who may consider Neurotransmitter XL
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Individuals with persistent stress, burnout, low mood, anxiety, sleep problems, brain fog, headaches, or fluctuating energy.
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Patients and clinicians exploring the biochemical links among mood, stress physiology, immunity, and cellular energy.
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Cases where prior testing of a single neurotransmitter gave incomplete or conflicting clues.
Note: This is an advanced panel. Optimal value comes from interpretation by clinicians trained in neurochemistry, metabolism, and functional medicine.
What’s included (high-level)
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Neurotransmitters: Dopamine, Noradrenaline, Adrenaline, Serotonin, GABA, Glutamate
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Tryptophan–Kynurenine Pathway: Tryptophan, Kynurenine, pathway metabolites (e.g., quinolinic acid), and enzyme-activity context (IDO, KMO)
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Catecholamine metabolism: Breakdown products and COMT/MAO pathway context
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Cofactor status (functional context): B6, B12, folate, Vitamin C, Niacin/Nicotinamide/NAD, SAM/methylation balance, BH4 context
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Mitochondrial and nitrosative stress context: Pyruvate, lactate, citrate, select dicarboxylic acids (e.g., suberic acid), citrulline
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Immune activation and microbiome-linked markers: Neopterin, TMAO context
(Exact marker lists can vary by region and laboratory updates. Refer to your report for the complete analyte panel.)
Sample type and process
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At-home urine collection (typically first-morning specimen, per kit instructions)
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Prepaid return to the laboratory
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Secure digital results
Interpreting common patterns (examples)
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High adrenaline/noradrenaline with stress symptoms may reflect autonomic overload; interpretation considers clearance capacity (COMT/MAO routes), nutrient cofactors, and blood pressure or glycemic triggers.
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Low serotonin with high kynurenine-to-tryptophan ratio suggests stress/inflammation-driven diversion away from serotonin toward kynurenine metabolites; clinicians often review inflammatory load, sleep, and cofactor sufficiency (B6, folate, B3/NAD).
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GABA–glutamate imbalance can manifest as restlessness, overexcitability, or cognitive fatigue; evaluation looks at inhibitory tone versus excitatory drive and the role of sleep, stress, and nutrients.
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Mitochondrial strain signatures (e.g., altered pyruvate/lactate; elevated suberic acid) can track with low energy despite adequate sleep and nutrition, guiding attention to mitochondrial supports and workload modulation.
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Neopterin elevation points clinicians to immune activation that often correlates with IDO/KMO shifts and reduced serotonin availability.
These patterns are illustrative; clinical decisions depend on your complete history, medications, diet, and goals.
Important notes and safety
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This test is intended for professional interpretation by doctors, clinics, or licensed therapists.
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Do not change medications or start targeted supplements without clinical guidance—especially if you take agents that affect serotonin or catecholamines.
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Dosages and treatment examples mentioned in laboratory literature are for clinician use and may not apply to your case.
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Biomarkers included in this panel:
3-OH-Kynurenine
Adrenaline
Betaine
Betaine, also known as trimethylglycine (TMG), is a naturally occurring nutrient derived primarily from choline and found abundantly in foods such as beets, spinach, and whole grains. It serves as a key methyl donor in the body, supporting the conver
Learn moreCarnitine
Choline
Choline is an essential nutrient that plays a foundational role in brain health, liver function, methylation, and neurotransmitter synthesis. It serves as both a structural building block for cell membranes and a biochemical precursor for several key
Learn moreCitrate
Citrate is a key organic acid and an essential intermediate in the citric acid (Krebs) cycle, the core metabolic pathway responsible for producing energy (ATP) within the mitochondria. On the Neurotransmitter XL panel, citrate is used as a functional
Learn moreCitrulline
Dopamine
Dopamine is a key neurotransmitter involved in motivation, focus, movement, and emotional balance. On the Neurotransmitter XL panel, it’s measured alongside related catecholamines and cofactors to provide a complete view of the body’s str
Learn moreGABA
Glutamate
IDO-Activity
KMO-Activity
Kynurenic acid
Kynurenine
Kynurenine is a central metabolite in the tryptophan degradation pathway, known as the kynurenine pathway, which plays a vital role in neurotransmitter balance, immune regulation, mitochondrial energy production, and oxidative stress control. It sits
Learn moreLactate
Nicotinamide adenine dinucleotide (NAD+) is a vital coenzyme present in every cell of the body. It plays a central role in energy production, redox balance, DNA repair, and cellular signaling. On the Neurotransmitter XL panel, NAD+ serves as a critic
Learn moreNeopterin
Nicotinamide
Nicotinic acid
Noradrenaline
Phenylalanine
Phenylalanine is an essential aromatic amino acid that serves as the biochemical starting point for several critical compounds in the body, including the catecholamine neurotransmitters — dopamine, noradrenaline, and adrenaline. On the Neurotra
Learn morePyruvate
Quinolinic acid
Quinolinic acid is a key intermediate in the kynurenine pathway, the primary route by which the amino acid tryptophan is metabolized into nicotinamide adenine dinucleotide (NAD+)—a molecule essential for cellular energy, mitochondrial function,
Learn moreS- Adenosylmethionine
S-Adenosylmethionine (SAM)—also known as SAMe—is a vital methyl donor molecule that supports hundreds of biochemical reactions throughout the body. Formed from the amino acid methionine and ATP, SAM plays an essential role in methylation,
Learn moreSAM/SAH Ratio
The SAM/SAH Ratio is one of the most powerful functional indicators of methylation efficiency in the human body. It represents the balance between S-Adenosylmethionine (SAM)—the body’s primary methyl donor—and S-Adenosylhomocysteine
Learn moreSerotonin
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
Learn moreSuberic acid
Trimethylamine
Tryptophan
Tryptophan is an essential amino acid and the biochemical foundation for serotonin, melatonin, and NAD+ production, linking mood regulation, sleep, immune function, and energy metabolism. On the Neurotransmitter XL panel, it provides insight int
Learn moreTyrosine
Tyrosine is a non-essential amino acid derived from phenylalanine, and it plays a pivotal role in the body’s ability to generate catecholamine neurotransmitters — dopamine, noradrenaline, and adrenaline. These compounds regulate motivatio
Learn more