Quick answer: Organic acids testing (OAT) — analysis of 70+ metabolic intermediates in urine — provides a biochemical snapshot of mitochondrial function, Krebs cycle efficiency, neurotransmitter metabolism, B-vitamin status, oxidative stress markers, dysbiosis markers, and fatty acid oxidation. It is one of functional medicine’s most comprehensive single-specimen metabolic assessments, capable of identifying cellular energy deficits years before clinical disease becomes apparent.
What Are Organic Acids and Why Do They Matter?
Organic acids are carbon-containing compounds — primarily metabolic intermediates — excreted in urine. They reflect the functional activity of enzymes, cofactors, and metabolic pathways throughout the body. Because mitochondria perform most cellular energy metabolism and are exquisitely sensitive to nutrient deficiencies, toxins, and genetic variants, urinary organic acids effectively function as a real-time readout of mitochondrial health.
The foundational work of Nobel laureate Hans Krebs (Krebs cycle, 1937) established that most cellular energy (ATP) production runs through the tricarboxylic acid (TCA) cycle — converting acetyl-CoA (derived from fats, carbohydrates, and proteins) into CO2 and reducing equivalents (NADH, FADH2) that feed the electron transport chain to generate ATP. When any enzyme or cofactor in this cycle is impaired, upstream metabolic intermediates accumulate and spill into urine — creating the distinctive organic acid patterns detected on OAT.
The clinical application of OAT in metabolic medicine began with inborn errors of metabolism (IEM) in neonates — PKU (phenylketonuria), maple syrup urine disease, organic acidurias — where enzyme defects cause massive accumulation of specific organic acids. Functional medicine extended this concept to acquired functional deficiencies — where the same pathways are impaired not by genetic enzyme loss but by nutrient depletion, toxic inhibition, or mitochondrial damage — at lower-grade levels than classic IEM but with significant clinical consequences.
Mitochondrial Markers: Reading the Krebs Cycle
Krebs cycle organic acid markers: Citrate, isocitrate, aconitate, succinate, fumarate, malate, and 2-oxoglutarate (α-ketoglutarate) are the direct intermediates of the TCA cycle. Accumulation patterns diagnose specific enzymatic impairments or cofactor deficiencies. For example: elevated succinate with normal fumarate suggests impaired succinate dehydrogenase (Complex II of ETC — iron-sulfur cluster dependent, sensitive to iron deficiency and heavy metal toxicity); elevated 2-oxoglutarate may indicate thiamine (B1) deficiency (thiamine is required for α-ketoglutarate dehydrogenase); generally elevated Krebs cycle intermediates with reduced ATP markers suggest global mitochondrial dysfunction.
Fatty acid oxidation markers: Adipate, suberate, ethylmalonate are dicarboxylic acids that accumulate when fatty acid β-oxidation is impaired. This impairment can result from carnitine deficiency (carnitine is the shuttle that transports long-chain fatty acids into mitochondria — deficiency produces fatigue, muscle weakness, and cardiomyopathy), riboflavin (B2) deficiency (required for electron transfer flavoprotein, a key component of fatty acid oxidation), CoQ10 deficiency, or mitochondrial damage. Elevated adipate/suberate/ethylmalonate is one of the most common findings in patients with chronic fatigue, muscle weakness, and exercise intolerance. L-carnitine supplementation at 1–3g/day typically normalizes these markers in deficiency states.
Pyruvate metabolism markers: Elevated pyruvate, lactate, or the lactate:pyruvate ratio indicates impaired pyruvate entry into the TCA cycle — typically thiamine (B1) deficiency or pyruvate dehydrogenase (PDH) impairment. PDH requires thiamine pyrophosphate, lipoic acid, and pantothenic acid (B5) as cofactors — all three must be adequate for efficient pyruvate oxidation. Chronic alcohol use, bariatric surgery, and restrictive diets commonly produce thiamine deficiency. Elevated lactate without elevated pyruvate suggests impaired ETC (insufficient NADH oxidation back to NAD+), signaling mitochondrial electron transport dysfunction.
Neurotransmitter Metabolism Markers
OAT uniquely assesses neurotransmitter synthesis and catabolism pathways, providing indirect insight into central neurotransmitter activity through metabolite measurement:
Dopamine and catecholamine markers: Homovanillic acid (HVA) is the primary dopamine metabolite, measured as the ratio of HVA to vanilmandelic acid (VMA, norepinephrine metabolite). Low HVA:VMA ratio suggests impaired dopamine synthesis relative to norepinephrine — associated with ADHD, depression, Parkinson’s risk. Elevated HVA may indicate dopamine excess or tyrosine supplementation. Tyrosine → L-DOPA (requiring BH4 cofactor and iron) → Dopamine (requiring pyridoxal-5′-phosphate/B6) → Norepinephrine (requiring Vitamin C and copper) → Epinephrine. Each conversion step requires specific nutrients, and OAT patterns can identify which step is rate-limited.
Serotonin marker — 5-HIAA (5-Hydroxyindoleacetic acid): The primary urinary serotonin metabolite. Low 5-HIAA indicates reduced serotonin turnover — potentially from tryptophan deficiency (tryptophan competes with branched-chain amino acids for BBB transport), B6 deficiency (required for tryptophan decarboxylation to serotonin), or intestinal inflammation reducing enterochromaffin serotonin production. High 5-HIAA may indicate carcinoid tumor (cardinal finding), high tryptophan intake, or Hartnup disease. Context matters enormously — the pattern alongside other markers is diagnostic, not the absolute value alone.
GABA and glutamate markers — GABA, glutamate, 2-oxoglutarate relationship: GABA (γ-aminobutyric acid) is synthesized from glutamate by glutamic acid decarboxylase (GAD, requires B6). Low GABA suggests B6 functional deficiency, glutamate excess, or GAD enzyme impairment (GAD65 antibodies are the autoimmune marker of Type 1 diabetes and occur in stiff person syndrome). Elevated glutamate alongside low GABA suggests an excitatory/inhibitory neurotransmitter imbalance — a pattern clinically associated with anxiety, seizure susceptibility, and neuroinflammation.
Oxidative Stress, Detoxification, and Methylation Markers
Oxidative stress markers: 8-Hydroxydeoxyguanosine (8-OHdG) — the gold-standard marker of oxidative DNA damage — measures the extent to which reactive oxygen species are attacking nuclear and mitochondrial DNA. Elevated 8-OHdG is associated with accelerated aging, increased cancer risk, and mitochondrial dysfunction. Isoprostane (8-isoprostane) — formed by free-radical peroxidation of arachidonic acid — is a highly specific oxidative stress marker. Both are measurable on comprehensive OAT panels.
Methylation and B-vitamin markers: Methylmalonic acid (MMA) — the most sensitive functional marker of Vitamin B12 status. MMA is a substrate of methylmalonyl-CoA mutase, which requires adenosylcobalamin (active B12 form) as a cofactor. Elevated MMA indicates functional B12 deficiency even when serum B12 appears normal — subcellular B12 availability may be impaired by genetic variants (MTHFR C677T, MTRR A66G, MTR A2756G), mercury toxicity (mercury inhibits methionine synthase), or elevated homocysteine. This is one of the most clinically important OAT findings — functional B12 deficiency causes peripheral neuropathy, megaloblastic anemia, cognitive impairment, and psychiatric symptoms, and serum B12 can be deceptively normal while MMA is elevated.
Formiminoglutamate (FIGlu) — elevated in functional folate deficiency. Quinolinate — an excitatory neurotoxin produced by the kynurenine pathway (tryptophan → IDO enzyme activation → kynurenine → quinolinate). IDO (indoleamine-2,3-dioxygenase) is activated by inflammation — shunting tryptophan away from serotonin toward quinolinate, providing a direct mechanistic link between inflammation, reduced serotonin (depression), and elevated glutamatergic excitotoxicity (elevated quinolinate → NMDA receptor agonism → neuroinflammation). This explains the cytokine hypothesis of depression biochemically — elevated quinolinate is both the marker and the mechanism of inflammation-induced depression.
Dysbiosis Markers: The Gut-Mitochondria Connection
OAT includes a panel of microbial metabolite markers that reflect gut microbiome activity — particularly bacterial and fungal overgrowth producing distinctive metabolites:
Bacterial dysbiosis markers: 4-Hydroxyphenylacetic acid and 4-Hydroxyphenylpropionic acid — produced by Clostridium species and other anaerobes fermenting phenylalanine/tyrosine; elevated in SIBO and dysbiosis, correlate with behavioral symptoms (Clostridia species produce 3-(3-hydroxyphenyl)-3-hydroxypropionic acid/HPHPA — a dopamine agonist associated with ADHD-like symptoms in children with dysbiosis). Indican/indole/skatole — products of tryptophan fermentation by Escherichia coli and other proteolytic bacteria; elevated in SIBO and putrefactive dysbiosis.
Fungal/Candida dysbiosis markers: Arabinose, tartaric acid, citramalic acid — Arabinose is the most specific OAT marker for Candida and Saccharomyces overgrowth. Urinary arabinose was validated by Shaw et al. (Autism Research Institute) as correlating with improved behavior in autism spectrum disorder upon Candida treatment — a landmark observation in the gut-brain-behavior literature. Tartaric acid (not to be confused with food-derived tartrate) is produced exclusively by Candida species. Elevated arabinose and tartaric acid together strongly suggest significant intestinal fungal overgrowth warranting antifungal and prebiotic intervention.
The Clinical Value of Comprehensive OAT: Case Patterns
Chronic fatigue/CFS pattern: Elevated adipate, suberate, ethylmalonate (fatty acid oxidation impairment), elevated lactate:pyruvate ratio (ETC impairment), low citric acid cycle intermediates (substrate deficiency), elevated oxidative stress markers. Treatment targets: L-carnitine (1-3g/day), riboflavin (B2, 100-400mg/day), CoQ10 (200-600mg/day as ubiquinol), thiamine (100-600mg/day benfotiamine or TTFD form), acetyl-L-carnitine (1-2g/day for mitochondrial membrane function), magnesium malate or glycinate (500-1000mg/day), and alpha-lipoic acid (300-600mg/day).
Neurodevelopmental/behavioral pattern: Elevated HPHPA (Clostridia), elevated arabinose and tartaric acid (Candida), low HVA (dopamine deficiency), low 5-HIAA (serotonin deficiency), elevated quinolinate (neuroinflammatory tryptophan shunting). Treatment: targeted antimicrobial/antifungal followed by probiotic restoration, B6 (100-200mg/day P5P form), L-tyrosine (500-2000mg/day), tryptophan or 5-HTP (100-300mg/day), methylated B-vitamins.
Metabolic syndrome/pre-diabetes pattern: Elevated pyruvate (PDH impairment from thiamine deficiency), low Krebs cycle intermediates (insulin resistance impairs TCA function), elevated oxidative stress (8-OHdG, isoprostane from chronic hyperglycemia-driven ROS), elevated HVA:VMA ratio anomalies (autonomic dysfunction), elevated methylmalonate (B12 functional deficiency from metformin use — metformin inhibits intestinal Vitamin B12 absorption in 30% of users). Treatment: thiamine (benfotiamine preferred for metabolic), acetyl-L-carnitine, alpha-lipoic acid (clinically validated for diabetic neuropathy), CoQ10, B12 optimization.
Collecting and Interpreting OAT
OAT is collected as a first-morning urine specimen — the most concentrated and metabolically representative. Standard collection: first void discarded (most concentrated, may overrepresent some markers), second void collected after 12-hour overnight fast. Patient should avoid artificial food dyes (citric acid cycle artifactual elevation), riboflavin supplements (B2 produces false patterns), large doses of vitamin C, and apple/pear juice (fructose metabolites alter some markers) for 48 hours before collection. Most panels process 70–100 metabolites via GC-MS (gas chromatography-mass spectrometry) or LC-MS/MS — the gold standards for metabolite identification and quantification.
Leading OAT panels include Great Plains Laboratory (now Mosaic Diagnostics) OAT, Genova Diagnostics Comprehensive Organix Profile, and Doctor’s Data Urine Toxic Metals + Organic Acids combination panel. Each has slightly different marker panels and reference ranges — clinical interpretation must account for the specific methodology used.
OAT at The Private Practice
At The Private Practice, organic acids testing is a foundational component of our comprehensive metabolic evaluation — particularly for patients with chronic fatigue, fibromyalgia, cognitive symptoms, or complex multisystem presentations. OAT results guide targeted mitochondrial support protocols, connecting to our work in ketogenic metabolic therapy, gut restoration, longevity supplementation, and heavy metal/toxin evaluation.
Frequently Asked Questions
Is organic acids testing covered by insurance?
Standard OAT panels through specialty functional medicine labs (Great Plains/Mosaic Diagnostics, Genova Diagnostics) are typically not covered by conventional insurance, as they are considered “investigational” or “experimental” by most payers despite being standard of care in metabolic medicine for inborn errors of metabolism. Self-pay costs range from $200–$400 for comprehensive panels. Some components — serum B12, methylmalonic acid, folate — may be individually ordered through conventional labs (Quest, Labcorp) and may have insurance coverage. Medicare and some commercial insurers cover MMA when there is documented B12 deficiency workup. Healthcare sharing accounts (HSA/FSA) typically cover OAT as a legitimate medical expense.
What is the difference between OAT and standard metabolic panel lab tests?
Standard metabolic panels (CMP, BMP) assess organ function at the tissue level — liver enzymes, kidney function (creatinine, BUN), electrolytes, blood glucose. They detect overt organ damage or failure. Organic acids testing operates at the cellular/subcellular level — measuring the products of intracellular metabolic pathways that conventional tests cannot access. A patient can have perfectly normal liver function tests, kidney function, and blood glucose while having significant mitochondrial dysfunction, B-vitamin deficiencies, oxidative stress, and neurotransmitter metabolism abnormalities detectable on OAT. OAT and conventional labs are complementary — not competing — assessments operating at different levels of biological organization.
How does CoQ10 deficiency show up on organic acids testing?
CoQ10 (ubiquinone/ubiquinol) is essential for electrons to move through Complexes I and II of the mitochondrial electron transport chain to Complex III. CoQ10 deficiency produces a pattern of impaired electron transport reflected in elevated Krebs cycle intermediates (succinate, fumarate, malate — the substrates that cannot donate electrons normally), elevated lactate:pyruvate ratio (NAD+ cannot regenerate without functional ETC), and elevated fatty acid oxidation markers (ETF requires CoQ10 for electron acceptance). Elevated 3-methylglutaconic acid is a specific OAT marker for mitochondrial dysfunction that sometimes correlates with CoQ10 deficiency. Primary CoQ10 measurement requires plasma CoQ10 assay (normal ubiquinol range: 0.40–1.50 µg/mL); statin use is the most common acquired cause of functional CoQ10 depletion (HMG-CoA reductase inhibition blocks the same pathway as CoQ10 synthesis).
Can OAT help with ADHD or autism spectrum disorder?
Yes — OAT has substantial literature support in neurodevelopmental conditions. Shaw’s pioneering work at Great Plains Laboratory documented that children with autism spectrum disorder (ASD) had significantly elevated arabinose (Candida overgrowth), HPHPA (Clostridium species producing dopamine-pathway-disrupting metabolites), and tartaric acid vs. typically developing controls. Antifungal treatment (nystatin, fluconazole) reducing arabinose produced behavioral improvements in multiple case series. In ADHD, OAT commonly shows: low HVA (dopamine deficiency), elevated HPHPA (Clostridia producing HPHPA which competitively inhibits dopamine beta-hydroxylase), low 5-HIAA, and oxidative stress markers. These findings support targeted nutritional and microbiome interventions as adjuncts or alternatives to stimulant medications in appropriately selected cases, particularly when conventional treatments have been suboptimal.
To schedule a comprehensive organic acids and mitochondrial function evaluation at The Private Practice, call (810) 206-1402 or visit theprivatepractice.co. We use OAT as part of our comprehensive metabolic assessment to identify and treat the root causes of fatigue, brain fog, chronic pain, and metabolic dysfunction at the cellular level.