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.