E2 ModeratePreliminaryPEM not requiredCross-SectionalPeer-reviewedReviewed
Low levels of serum acylcarnitine in chronic fatigue syndrome and chronic hepatitis type C, but not seen in other diseases.
Kuratsune, H, Yamaguti, K, Lindh, G et al. · International journal of molecular medicine · 1998 · DOI
Quick Summary
Researchers measured a substance called acylcarnitine in the blood of people with ME/CFS and compared it to healthy people and those with other diseases. They found that people with ME/CFS had significantly lower levels of this substance, and this same pattern appeared in both Japanese and Swedish patients. Importantly, this low level was only seen in ME/CFS and one other condition (chronic hepatitis C), not in other common diseases like diabetes or high blood pressure.
Why It Matters
This study identifies a potential biological marker—low acylcarnitine—that may be characteristic of ME/CFS across different populations (Japanese and Swedish), suggesting a fundamental metabolic abnormality. Finding disease-specific biomarkers is critical for ME/CFS, where diagnosis remains clinical, and this work supports the biological basis of the condition rather than it being psychiatric in origin.
Observed Findings
- Serum acylcarnitine levels were significantly lower in Swedish ME/CFS patients (n=57) compared to Swedish healthy controls (p<0.001).
- Serum acylcarnitine deficiency was significantly decreased in Japanese ME/CFS patients compared to healthy controls (p<0.001).
- Among Japanese patients with various diseases studied (CFS, hematological malignancies, chronic pancreatitis, hypertension, diabetes mellitus, chronic hepatitis type C, psychiatric diseases), only CFS and chronic hepatitis type C showed significant ACR deficiency (p<0.001).
- Baseline serum ACR and FCR levels differed significantly between Japanese and Swedish healthy control populations (p<0.001).
Inferred Conclusions
- Acylcarnitine deficiency is a characteristic abnormality of ME/CFS that appears across different ethnic populations.
- Acylcarnitine deficiency is not a general marker of disease but appears specific to certain conditions, with only CFS and chronic hepatitis type C showing this pattern among diseases studied.
- The finding suggests a specific metabolic dysfunction in ME/CFS rather than a nonspecific response to chronic illness.
Remaining Questions
- Does acylcarnitine deficiency appear in all ME/CFS patients or only specific subgroups, and does severity correlate with symptom burden?
- Is the acylcarnitine deficiency a primary cause of ME/CFS symptoms or a secondary consequence of the underlying disease process?
What This Study Does Not Prove
This study does not establish whether low acylcarnitine causes ME/CFS symptoms or is merely a consequence of the disease. The cross-sectional design cannot determine whether acylcarnitine levels change over time or predict disease outcomes. Additionally, the study does not establish whether this finding represents a universal characteristic across all ME/CFS patients or only certain subgroups.
Tags
Symptom:Fatigue
Biomarker:MetabolomicsBlood Biomarker
Method Flag:Weak Case DefinitionSmall SampleExploratory Only
Metadata
- DOI
- 10.3892/ijmm.2.1.51
- PMID
- 9854142
- Review status
- Editor reviewed
- Evidence level
- Single-study or moderate support from human research
- Last updated
- 12 April 2026
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
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