Urinary Biomarkers in Myalgic Encephalomyelitis (M.E.): Systematic Review Summary

Purpose

This page summarises findings from research reviewing urinary biomarkers in Myalgic Encephalomyelitis (M.E./ME/CFS). It explains whether urine-based testing can identify consistent biological patterns and support diagnosis, while outlining current limitations.

Key Points

1. Overall Findings

• There is no single validated urinary biomarker for M.E.
• However, research shows repeated patterns of metabolic disruption
• Findings suggest M.E. involves systemic biological dysfunction, not simply fatigue

2. Evidence of Metabolic Dysfunction

• Changes in metabolites linked to:
  • Glycolysis (energy production pathway)
  • Krebs (TCA) cycle activity
• Altered energy-related compounds indicate:
  • Impaired cellular energy production
  • Reduced metabolic efficiency

3. Mitochondrial and Energy Pathway Changes

• Abnormal levels of:
  • Lactate (suggesting increased anaerobic metabolism)
  • Pyruvate (altered energy balance)
  • Acylcarnitines (linked to fatty acid transport in mitochondria)
• These findings support theories of:
  • Mitochondrial dysfunction
  • Reduced energy availability under stress

4. Amino Acid and Protein Metabolism

• Altered levels of amino acids such as:
  • Glutamine / glutamate
  • Phenylalanine / tyrosine
  • Branched-chain amino acids
• May indicate:
  • Increased protein breakdown
  • Altered stress-response metabolism

5. Purine and ATP Metabolism

• Changes in metabolites related to:
  • ATP breakdown
  • Uric acid pathways
  • Hypoxanthine and xanthine
• Suggest disruption in the body’s energy currency system (ATP)

6. Oxidative Stress and Redox Imbalance

• Evidence of:
  • Increased oxidative stress markers
  • Altered antioxidant pathways
  • Redox imbalance
• Indicates higher cellular stress and impaired detoxification processes

7. Microbiome-Related Findings (Less Consistent)

• Some studies show differences in:
  • Gut-derived metabolites
  • Short-chain fatty acid products
• Findings are inconsistent and not yet reliable for clinical use

8. Comparison with Blood and Muscle Studies

• Muscle studies:
  • Show reduced energy production and abnormal lactate accumulation
• Blood studies:
  • Show consistent metabolic changes and hypometabolic patterns
• Urine studies:
  • Reflect the body’s “waste output” of these metabolic disruptions

9. Key Integrated Insight

• Across research, a consistent pattern emerges:
  • Reduced metabolic flexibility
  • Impaired energy production under demand
• Indicates a system-wide energy dysfunction rather than isolated abnormalities

10. Limitations of Current Research

• Small sample sizes
• Different diagnostic criteria used across studies
• Variations in testing methods
• Lack of standardisation in activity levels before testing

👉 These factors make it difficult to establish a single reliable biomarker

Target Audience

This information is intended for:

• People living with M.E.
• Carers and family members
• Healthcare professionals
• Researchers and advocates

Overall Outcome

This page highlights that while urinary biomarkers cannot yet diagnose M.E., they consistently point toward underlying metabolic disruption, particularly in energy production and oxidative stress pathways.

Understanding these patterns helps:

• Support the biological basis of M.E.
• Guide future research toward diagnostic biomarkers
• Improve understanding of disease mechanisms
• Reinforce the multi-system nature of the illness

Key Summary Statement

Current evidence shows that urinary biomarkers in M.E. reflect widespread metabolic and energy dysfunction, but no single diagnostic marker has yet been identified.