Mitochondria are the tiny energy-producing structures inside our cells. They generate the energy required for nearly every biological function in the body—including brain activity, muscle function, immune response, and detoxification. When mitochondrial function is impaired, a wide range of symptoms can occur, including fatigue, developmental delays, neurological symptoms, and gastrointestinal problems.
Research over the past two decades has shown that mitochondrial dysfunction may occur in a subset of children with autism spectrum disorders (ASD). In these cases, evaluating mitochondrial function can sometimes provide helpful insights into underlying metabolic issues that may be contributing to symptoms.
According to Jon Poling, M.D., J.D., neurologist and Medical Director of Athens Neurological Associates (and father of Hannah Poling), there is no single test that can definitively rule in or rule out mitochondrial disease. However, several non-invasive laboratory tests can help identify biochemical patterns that suggest mitochondrial dysfunction and determine whether further evaluation by a mitochondrial disease specialist is warranted.
Many of these screening markers are available through standard reference laboratories such as Quest Diagnostics, LabCorp, or WestCliff Laboratories.
Initial Blood Testing
Most screening tests are performed on fasting blood samples (fasting at least 4 hours).
Comprehensive Blood Chemistry (Metabolic Panel)
Important markers may include:
- Low bicarbonate (CO₂) – may suggest metabolic acidosis and mitochondrial dysfunction
- Elevated AST – can suggest a metabolic muscle disorder or mitochondrial stress
These markers are often visible on standard metabolic panels.
Complete Blood Count (CBC)
A CBC helps evaluate overall metabolic and immune health and can identify abnormalities sometimes seen with metabolic disorders.
Additional Blood Markers
These tests provide more specific metabolic information.
Creatine Kinase (CK)
Elevated levels may indicate metabolic muscle involvement.
Vitamin B12
Evaluated as part of overall metabolic assessment.
Methylmalonic Acid
Evaluated as part of overall metabolic assessment.
Leukocyte CoQ10
Evaluated as part of overall metabolic assessment.
Acylcarnitine Profile
Low carnitine levels may indicate impaired fatty acid metabolism.
Plasma Amino Acid Profile
Possible indicators of mitochondrial dysfunction include:
- Alanine to lysine ratio greater than 2.5 (normal approximately 1.5–2.5)
- Elevated glycine or proline
Metabolic Stress Markers
These tests are commonly used when evaluating mitochondrial function.
Serum Ammonia
Evaluated as part of metabolic stress assessment.
Serum Lactic Acid (Lactate)
Elevated lactate or abnormal lactate-to-pyruvate ratios may suggest mitochondrial dysfunction:
- Ratio 10–20 may be suggestive of mitochondrial imbalance
- Ratio >20 raises stronger concern for mitochondrial disease
- Ratio >40 is considered highly abnormal
Serum Pyruvic Acid (Pyruvate)
Evaluated alongside lactate for assessment of mitochondrial function.
Important Notes on Sample Handling
Certain metabolic markers—particularly ammonia, lactate, and pyruvate—are very sensitive to how blood samples are collected and processed.
Improper handling can produce false elevations.
Guidelines for proper sample collection (as described by Steve Kahler, M.D., Division of Genetics, University of Arkansas for Medical Sciences) include:
- Red blood cells lack mitochondria and produce lactate rapidly after collection.
- A tight tourniquet can cause temporary oxygen deprivation (ischemia), which artificially increases lactate levels.
Recommended collection methods include:
- Using a straight needle in a hand vein to obtain free-flowing blood placed into chilled perchloric acid.
- Using an indwelling catheter or butterfly needle without a tourniquet when possible.
- Some laboratories use fluoride (gray top) tubes, which stop the production of pyruvate and reduce unwanted lactate production.
Ideally, no tourniquet should be used when drawing samples for these markers.
Helpful Surrogate Marker
A useful indirect marker for mitochondrial dysfunction is plasma alanine.
Elevated alanine may reflect increased pyruvate levels because pyruvate can be converted into alanine through the enzyme alanine transaminase (ALT).
A high alanine-to-lysine ratio greater than 2.5 may suggest an underlying mitochondrial imbalance.
Urine Testing
Urine testing is typically performed using a first-morning urine sample.
Urinalysis with pH
Helps assess metabolic acid-base balance.
Organic Acids Test
Organic acids testing can reveal metabolic byproducts that accumulate when mitochondrial pathways are impaired.
Possible indicators include:
- Increased short-chain dicarboxylic fatty acids (suggesting impaired beta-oxidation)
- Increased fumarate
- Increased malate
- Increased 3-methylglutaconate
Urine Amino Acids
Findings that may suggest mitochondrial dysfunction include:
- Alanine-to-lysine ratio greater than 2.5
- Increased glycine or proline
Urine Acylcarnitine Profile
Low carnitine levels may suggest impaired mitochondrial fatty acid transport.
Muscle Biopsy: Is It the “Gold Standard”?
There is no single gold standard test for mitochondrial disease.
In some cases, genetic testing alone can identify known mitochondrial syndromes such as:
- MERRF (Myoclonic Epilepsy with Ragged Red Fibers)
- MELAS (Mitochondrial Encephalopathy with Lactic Acidosis and Stroke-like Episodes)
- PEO (Progressive External Ophthalmoplegia)
- Kearns-Sayre Syndrome (KSS)
- MNGIE (Mitochondrial Neurogastrointestinal Encephalopathy)
Muscle biopsy can sometimes identify specific enzyme defects or metabolic abnormalities and may help guide targeted nutritional therapies.
However, there are important limitations:
- It is invasive and typically requires anesthesia.
- Only specialized laboratories can properly process mitochondrial muscle biopsies.
- False negatives can occur because mitochondrial abnormalities may not be evenly distributed in muscle tissue.
For these reasons, muscle biopsy and advanced genetic testing should generally be performed under the guidance of a specialist in metabolic or mitochondrial disorders.
Additional Considerations in Autism
Emerging research suggests that mitochondrial dysfunction may be present in a subset of individuals with autism, even when a classical mitochondrial disease is not diagnosed.
Factors that may contribute to mitochondrial stress include:
- Oxidative stress
- Chronic inflammation
- Environmental toxin exposure
- Nutritional deficiencies
- Impaired detoxification pathways
Because mitochondria are essential for brain development and neurological function, addressing underlying metabolic imbalances may be an important component of a comprehensive autism recovery strategy.
Important Disclaimer
The material contained within this document is not intended to replace the services and/or medical advice of a licensed healthcare practitioner, nor is it meant to encourage diagnosis or treatment of disease. This material has not been reviewed by the Food and Drug Administration (FDA) and is provided strictly for educational purposes.
Health Training Associates (and its associates and affiliates) does not accept legal responsibility for any problems arising from experimentation with the information described herein. Any application of the suggestions set forth in this document is at the reader’s discretion and sole risk. Implementation or experimentation with supplements, herbs, dietary changes, medications, or lifestyle modifications should always be discussed with your (or your child’s) personal physician before beginning.