ME/CFS Blood-Based Biomarkers
1 Beentjes et al. 2025 — Replicated Blood-Based Biomarkers for ME Not Explicable by Inactivity
Full Citation:: Beentjes SV, Miralles M{'e}haron A, Kaczmarczyk J, et al. Replicated blood-based biomarkers for myalgic encephalomyelitis not explicable by inactivity. EMBO Molecular Medicine. 2025;17(7):1868–1891. (Beentjes et al. 2025) DOI:: 10.1038/s44321-025-00258-8 PMID:: 40537675 / PMCID: PMC12254397 Study Design:: UK Biobank data (\(n=1{,}455\) ME/CFS cases, \(n=131{,}303\) population controls); mediation analysis; replication in All-of-Us cohort (\(n=9\) of 14 traits replicated) Key Findings::
- Hundreds of blood traits differ between ME/CFS cases and controls, including 116 significant in both female and male cohorts
- Biomarker pattern indicative of chronic inflammation, insulin resistance, and liver disease
- Critically: ME/CFS status affected only 1 of 3,237 traits via an activity-duration mediator — differences are not explained by reduced physical activity
- Post-exertional malaise subgroup showed more pronounced biomarker alterations
- 9 of 14 traits replicated in the independent All-of-Us cohortRelevance:: Landmark for ME/CFS biomarker research. The activity-independent replication directly refutes the deconditioning/inactivity explanation for ME/CFS biomarker findings. The chronic inflammation and insulin resistance pattern aligns with metabolic and immune dysfunction hypotheses. The PEM-severity correlation provides an objective anchor for a biological definition of post-exertional malaise. Certainty Assessment::
- *Quality:* High (EMBO Molecular Medicine; large UK Biobank cohort; two-cohort replication)
- *Sample:* $n=1{,}455$ ME cases (largest ME biomarker study to date)
- *Replication:* Partially replicated in All-of-Us independent cohort
- *Certainty:* 0.75
- *Limitation:* UK Biobank ME/CFS classification relies on self-report and clinical codes; individual traits lack diagnostic specificity; panel biomarker test not yet validated2 Leow et al. 2005 — Hypocortisolism in SARS-1 Survivors
Full Citation:: Leow MK-S, Kwek DS-K, Ng AW-K, Ong K-C, Kaw GJ-L, Lee LS-U. Hypocortisolism in survivors of severe acute respiratory syndrome (SARS). Clinical Endocrinology. 2005;63(2):197–202. (Leow et al. 2005) DOI:: 10.1111/j.1365-2265.2005.02325.x PMID:: 16060914 Study Design:: Prospective follow-up cohort of 61 SARS-1 survivors; dynamic endocrine testing at 3 months post-discharge; one-year follow-up for reversibility Key Findings::
- 39.3% (24/61) met criteria for central hypocortisolism consistent with secondary adrenal insufficiency
- 3.3% (2/61) had concomitant subclinical thyrotoxicosis; 4.9% (3/61) had central hypothyroidism
- Majority of hormonal dysfunction resolved within one year
- Central hypocortisolism pattern (low/normal ACTH, low cortisol) indicates pituitary or hypothalamic injury rather than primary adrenal failure; subsequent research identified ACE2 receptor expression on pituitary cells as the likely entry mechanism for SARS-CoVRelevance:: Foundational evidence that coronavirus infection can cause structural pituitary injury producing secondary adrenal insufficiency at clinically significant rates. Establishes proof-of-concept for post-viral pituitary damage as ME/CFS mechanism. The reversibility finding suggests early detection and management may prevent chronic HPA dysfunction. Certainty Assessment::
- *Quality:* High (prospective; Clinical Endocrinology; dynamic testing used)
- *Sample:* $n=61$ hospitalised SARS-1 survivors
- *Replication:* Consistent with COVID-19 pituitary case series (Carosi 2024)
- *Certainty:* 0.70 for SARS-1; extrapolation to post-COVID/ME-CFS inferential (certainty 0.50 for ME/CFS relevance)
- *Limitation:* Hospitalised cohort; ACE2 tropism specific to coronaviruses; generalisability to EBV/enterovirus triggers undemonstratedFull Citation:: Ruiz-Pablos M, Paiva B, Zabaleta A. Hypocortisolemic ASIA: a vaccine- and chronic infection-induced syndrome behind the origin of long COVID and myalgic encephalomyelitis. Frontiers in Immunology. 2024;15:1422940. (Ruiz-Pablos, Paiva, and Zabaleta 2024) DOI:: 10.3389/fimmu.2024.1422940 PMID:: 39044822 / PMCID: PMC11263040 Study Design:: Hypothesis/review article; mechanistic model synthesis Key Findings::
- Proposes that deficient CD4 T-cell viral control in HLA-DRB1 predisposed individuals leads to uncontrolled CD8/antibody response, including autoantibodies against pituitary antigens
- Autoimmune hypophysitis or direct pituitary cytopathic injury reduces ACTH output, producing secondary adrenal insufficiency
- Model predicts a reversibility window: early identification before long-lived autoreactive plasma cells become established may allow recovery of HPA function
- Unifies post-COVID ME/CFS, post-vaccine syndromes, and chronic infection-triggered ME/CFS under a shared neuroendocrine-immune mechanismRelevance:: Provides mechanistic framework connecting viral immune dysregulation to structural pituitary damage. Explains why post-COVID ME/CFS patients with autoimmune hypophysitis present with low-normal cortisol (not flagged by standard screening) and why dynamic testing is essential. The reversibility window concept has direct clinical management implications. Certainty Assessment::
- *Quality:* Medium (Frontiers in Immunology; hypothesis paper)
- *Sample:* Review/hypothesis; no primary data
- *Replication:* Model consistent with Leow 2005 and Carosi 2024 empirical data
- *Certainty:* 0.40 (hypothesis-level; mechanistically coherent but not directly tested in ME/CFS cohorts)
- *Limitation:* No primary clinical data; HLA-DRB1 specificity not established; vaccine-triggered cases require separate consideration from infection-triggered3 Carosi et al. 2024 — Hypopituitarism and COVID-19
Full Citation:: Carosi G, Cremaschi A, Giavoli C, Ferrante E, Mantovani G. Hypopituitarism and COVID-19. Pituitary. 2024;27(6):925–934. (Carosi et al. 2024) DOI:: 10.1007/s11102-024-01463-3 PMID:: 39560821 Study Design:: Narrative review of published case series and cohort studies; published November 2024 Key Findings::
- Variable degrees of pituitary deficiency documented across COVID-19 case series
- Both direct viral cytopathic effects and immune-mediated hypophysitis proposed as mechanisms; causation remains uncertain
- Pituitary defects may persist long after acute infection, potentially contributing to long COVID symptom burden
- Heterogeneous results across studies reflect different testing methodologies and hormonal cutoffsRelevance:: Extends SARS-1 evidence (Leow 2005) into COVID-19 context. Documents that pituitary involvement is a feature of SARS-CoV-2 infection. The persistence of pituitary defects post-infection is directly relevant to long COVID and post-COVID ME/CFS HPA dysfunction. Certainty Assessment::
- *Quality:* Medium-high (Pituitary journal; narrative review)
- *Sample:* Synthesis of multiple case series (heterogeneous)
- *Replication:* Consistent with Leow 2005 SARS-1 data
- *Certainty:* 0.55 (case series quality; causation uncertain; no ME/CFS-specific data)
- *Limitation:* Heterogeneous testing protocols; no ME/CFS-specific data; reversibility unclear