Summary
| Direction in ME/CFS | ↕ Inconsistent — reported as both higher and lower across studies, with no consistent direction |
|---|---|
| Category | Metabolic |
| Also described as | C0 |
| Compared against | HC (healthy controls) |
| Associated symptoms | Carnitine shuttle dysfunction |
| Test type | Blood test (serum / plasma / whole blood) |
| Source | Jinushi et al. 2023 — doi:10.1186/s12967-023-04347-4 |
| Condition atlas | ME/CFS Biomarker Atlas |
Trials, interventions and tests
Also sold as a nutrient or supplement
L-Carnitine / Acylcarnitines (supplement). Includes ALCAR and acylcarnitine complexes. This tag means the analyte is also available orally; it is not a product endorsement and a low or high level does not by itself justify supplementation.
Related Metabolic markers in ME/CFS
- C18 Acylcarnitine (stearoylcarnitine) ↑
- Lactate (blood) ↑
- C16 Acylcarnitine (palmitoylcarnitine) ↑
- Acylcarnitines (composite) ↑
- Serine ↓
- Sarcosine ↓
- Kynurenine ↑
- Ceramides (plasma) ↓
Full list: ME/CFS Biomarker Atlas.
Frequently asked questions
Is Free carnitine high or low in ME/CFS?
Mixed. Some studies report higher and others lower Free carnitine in ME/CFS compared with healthy controls, so no single direction is established. Source: Jinushi et al. 2023.
What symptoms is Free carnitine associated with in ME/CFS?
The cited literature associates this marker with Carnitine shuttle dysfunction. These are population-level associations and do not mean the marker causes the symptoms.
Which test measures Free carnitine?
It is measured as a blood test (serum / plasma / whole blood). Many of the cited studies used research-grade assays, so clinical availability may vary.
Is one abnormal Free carnitine result diagnostic of ME/CFS?
No. No single biomarker is diagnostic of ME/CFS. Free carnitine findings come from group comparisons, overlap considerably between patients and controls, and vary with study design, timing and comparison group. A result should be interpreted by a clinician alongside symptoms, history and other tests.
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Last reviewed: 2026-06-29 · Page generated from me-cfs.json · Browse: ME/CFS atlas · Biomarker Index · All marker pages
Disclaimer: This page is an educational synthesis of published, peer-reviewed research and is not medical advice. Biomarker findings vary across studies with case definitions, comparison groups, timing and assay methods. Direction of change reflects the predominant finding in the cited source and does not establish a diagnostic threshold. Discuss any test result with a qualified clinician.