Organic Acid Testing (OAT): Insight into Neurotransmitter Metabolism

Organic Acid Testing (OAT) is a powerful functional lab tool used in integrative and nutritional medicine to assess metabolic pathways, nutrient status, gut health, and especially the balance of neurotransmitters in the body. While it doesn’t measure neurotransmitters directly in the brain, it provides key information about how your body is producing, breaking down, and clearing neurotransmitters like dopamine, serotonin, norepinephrine, and GABA.

This makes OAT a valuable window into mood disorders, focus issues, sleep problems, anxiety, and even neurodegenerative risk.

🔍 What Are Organic Acids?

Organic acids are by-products of cellular metabolism, excreted in the urine. By analyzing these metabolites, OAT reveals how well certain biochemical pathways are functioning.

In the context of neurotransmitters, organic acids reflect:

• The precursors required to make them (e.g. amino acids)
  
• The cofactors needed for enzymatic reactions (e.g. B6, B12, folate, magnesium)
  
• The metabolic breakdown products (e.g. HVA for dopamine)
  
  

🧠 Key Neurotransmitter Metabolites in OAT

Below are the most relevant organic acids linked to neurotransmitter metabolism:

1. Homovanillic Acid (HVA)

🧪 Primary dopamine metabolite

• Elevated HVA → Possible dopamine excess, stress, stimulants, or impaired COMT/MAO activity
  
• Low HVA → Possible dopamine deficiency, low precursor (tyrosine), or cofactor insufficiency (B6, copper, vitamin C)
  
  

Clinical relevance: Seen in ADHD, Parkinson's risk, fatigue, mood disorders

2. Vanilmandelic Acid (VMA)

🧪 End-product of norepinephrine and epinephrine metabolism

• Elevated VMA → Stress response overload, adrenal hyperactivity
  
• Low VMA → Low norepinephrine/adrenaline output, possibly from B6, vitamin C, or copper deficiency
  
  

Often evaluated alongside HVA to assess dopamine-to-norepinephrine balance

3. 5-Hydroxyindoleacetic Acid (5-HIAA)

🧪 Primary serotonin metabolite

• Elevated 5-HIAA → Excess serotonin breakdown, possibly from high tryptophan intake or SSRIs
  
• Low 5-HIAA → Low serotonin production, B6 or folate deficiency, or gut dysbiosis
  
  

Low serotonin levels are linked to depression, anxiety, poor sleep, cravings

4. Quinolinic Acid & Kynurenic Acid

🧪 Products of tryptophan metabolism via the kynurenine pathway

• Imbalance → Neuroinflammation risk
  
• High quinolinic acid = Neurotoxic, glutamate excitotoxicity
  
• Low kynurenic acid = Less neuroprotection
  
  

Reflects inflammation-driven serotonin diversion and is relevant in chronic stress, autoimmunity, neurodegeneration

 

5. Pyridoxic Acid

🧪 Breakdown product of Vitamin B6

• B6 is required to convert:
  
  • 5-HTP → serotonin
    
  • L-DOPA → dopamine
    
  • Histidine → histamine
    
  • Glutamate → GABA
    
    

A low pyridoxic acid with low neurotransmitter metabolites may signal B6 deficiency

 

6. Glutaric & Succinic Acid

🧪 Related to mitochondrial function and glutamate metabolism

• Elevated in oxidative stress, mitochondrial dysfunction, or impaired GABA synthesis
  
• Can affect mood stability, irritability, or neurotoxicity
  
  

🧪 What OAT Can Tell You About Brain Chemistry

An Organic Acid Test provides indirect insight into: