Diagnosis & Testing

There is no single blood test for ME/CFS. This is what the diagnostic criteria actually require, and exactly which tests to ask for at each level of access.

Diagnosis & Testing

How ME/CFS is Diagnosed

There is currently no single confirmatory lab test for ME/CFS. Diagnosis is clinical - based on symptom criteria after ruling out other conditions. However, specific testing plays a crucial role in supporting the diagnosis and managing comorbidities.

TL;DR — Key Takeaways
  • There is no single diagnostic test - ME/CFS is diagnosed by clinical criteria (IOM 2015) requiring PEM, unrefreshing sleep, and cognitive impairment or orthostatic intolerance.
  • Testing serves to rule out other conditions and identify comorbidities - not to confirm ME/CFS itself.
  • Tier 1 tests (CBC, thyroid, iron, vitamin D, B12, cortisol, ECG) should be done by any GP.
  • Tier 2 adds autonomic testing (NASA lean test, tilt table) and immune markers.
  • Tier 3 (GPCR autoantibodies, 2-day CPET, NeuroQuant MRI) is specialist/research-level.
  • Diagnosis typically takes 5-14 years - arming yourself with the IOM 2015 criteria speeds this up.
Important ME/CFS is a diagnosis of inclusion - meaning the symptoms themselves confirm it - not merely a "diagnosis of exclusion" (only after ruling everything else out). However, ruling out treatable conditions that can cause similar symptoms remains essential.

Diagnostic Criteria Comparison

Criteria Set Year Key Requirements Notes
IOM/NAM 2015
Most used clinically		 2015 Substantial impairment + PEM + unrefreshing sleep + cognitive impairment OR orthostatic intolerance; present ≥50% of time at moderate-severe intensity for ≥6 months Recommended by CDC; most accessible to primary care; introduced SEID terminology option
Canadian Consensus Criteria (CCC) 2003 Fatigue + PEM + sleep dysfunction + pain + neurological/cognitive + autonomic/neuroendocrine/immune symptoms (minimum numbers from each category) Selects more severely affected patients; preferred by many ME specialists; most widely used in research
International Consensus Criteria (ICC) 2011 Neurological impairment + immune/GI/genitourinary impairment + energy production/transport impairment; PEM is central Most restrictive; identifies the most severe subset; uses term "ME" exclusively
Fukuda/CDC 1994 1994 Clinically evaluated, unexplained, persistent fatigue ≥6 months + ≥4 of 8 symptoms Broader (no PEM required); used in much historical research; now largely superseded for clinical use

Recommended Testing

The U.S. ME/CFS Clinician Coalition 2021 Testing Recommendations provide comprehensive guidance. Testing serves to rule out alternative diagnoses, identify comorbidities, and guide treatment.

Essential First-Line
  • Complete blood count (CBC) with differential
  • Comprehensive metabolic panel (CMP)
  • TSH, free T3, free T4 (thyroid)
  • ESR and CRP (inflammation markers)
  • ANA screen (autoimmunity)
  • Ferritin, serum iron, TIBC (iron stores)
  • Vitamin D (25-OH) and B12 levels
  • Urinalysis
  • Fasting glucose and HbA1c (diabetes)
Recommended Second-Line
  • NK cell function panel (not just count)
  • EBV panel (VCA IgG/IgM, EA-D, EBNA)
  • HHV-6 and CMV IgG antibodies
  • Cortisol (morning, and sometimes ACTH stim test)
  • Celiac antibodies (anti-tTG IgA)
  • DHEA-S, sex hormones
  • Lyme disease serology (ELISA + Western blot)
  • RBC magnesium (not serum)
  • Urinary organic acids / amino acids
Autonomic Testing
  • Tilt table test - gold standard for POTS/NMH
  • 10-minute standing test (NASA lean test) - bedside POTS screening; heart rate & BP every 2 min for 10 min
  • 24-hour Holter monitor - resting tachycardia, arrhythmias
  • QSART (quantitative sudomotor axon reflex test) - autonomic small fiber testing
  • Heart rate variability (HRV) - objective autonomic function measure
PEM Confirmation (Research)
  • 2-Day CPET (Cardiopulmonary Exercise Test) - only objective test that confirms PEM. ME/CFS patients show significant drop in VO2max and anaerobic threshold on day 2. Healthy people and most other chronic diseases do not. Important: requires a specialist and carries risks of triggering severe PEM.
  • Cognitive function testing - computer-based before and after cognitive challenge
  • Actometry - wrist accelerometry to objectively measure activity patterns

Additional Specialist Testing

TestWhat it ShowsWhen to Consider
Sleep study (PSG) Sleep apnea, sleep architecture, periodic limb movement Unrefreshing sleep, snoring, witnessed apneas
Skin punch biopsy (intraepidermal nerve fiber density) Small fiber neuropathy Burning pain, autonomic symptoms, strong clinical suspicion
SPECT or PET brain imaging Reduced cerebral blood flow, neuroinflammation Primarily research; emerging diagnostic utility
Serum or plasma GPCR autoantibodies β₂AR, M3R, M4R autoantibodies Available at Charité/research labs; guides immunoadsorption candidacy
Urine mast cell mediators (histamine, prostaglandin D2, tryptase) Mast cell activation syndrome (MCAS) Multi-system reactions to foods/chemicals, flushing, hives
Stool microbiome analysis Gut dysbiosis patterns Prominent GI symptoms; guides probiotic/dietary strategies
Lactulose/mannitol ratio Intestinal permeability ("leaky gut") GI symptoms, food sensitivities
Mitochondrial function testing (fibroblasts, ATP production) Mitochondrial energy deficits Specialized research labs; not standard clinical testing yet

Testing Guide

Testing by Access Level: What Your PCP Can Order vs. Specialist / Out-of-Pocket

Not all testing relevant to ME/CFS is covered by standard insurance. Understanding which tests are typically covered vs. require specialist referral or out-of-pocket payment helps patients and providers plan effectively.

TL;DR — Key Takeaways
  • Tier 1 (any GP, usually insurance-covered): CBC, CMP, TSH, ferritin, vitamin D, B12, cortisol, ESR/CRP, ANA, NASA lean test.
  • Tier 2 (specialist-guided): EBV/HHV-6 panel, NK cell function, tilt table, brain MRI, 2-day CPET for disability documentation.
  • Tier 3 (out-of-pocket, research-adjacent): GPCR autoantibodies, CIRS biomarker panel, urine MCAS panel, skin biopsy for SFN, NeuroQuant MRI.
  • The IOM 2015 criteria require NO specific test to diagnose ME/CFS - testing rules out alternatives and identifies treatable comorbidities.
  • Document everything. Medical records are yours to request. Bring printed criteria to appointments.
Source Testing recommendations based primarily on the U.S. ME/CFS Clinician Coalition 2021 Testing Recommendations[33] and clinical guidance from Bateman Horne Center. Insurance coverage varies by plan and country; always verify with your insurer. ICD-10 coding as G93.3 (Post-viral fatigue syndrome) or R53.82 (Chronic fatigue, unspecified) affects reimbursement.

Tier 1: Standard PCP-Ordered, Typically Insurance-Covered

These are tests a primary care physician can order on standard laboratory requisitions. Most are covered under routine illness workup by major US and EU/UK insurers. They serve to rule out other diagnoses and identify treatable comorbidities.

Blood / Lab - Standard
  • Complete blood count (CBC) with differential - rules out anemia, infection, blood disorders
  • Comprehensive metabolic panel (CMP) - liver, kidney, electrolytes, glucose
  • TSH + free T4 - thyroid disease (underactive thyroid mimics ME/CFS)
  • Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) - inflammation markers
  • Antinuclear antibody (ANA) screen - autoimmunity screen
  • Ferritin, serum iron, TIBC - iron deficiency (a common and treatable cause of fatigue)
  • 25-OH Vitamin D - deficiency is common and treatable
  • Serum B12 and folate
  • Urinalysis - rules out kidney disease, infection
  • Fasting glucose + HbA1c - diabetes
  • Lipid panel
  • Celiac antibodies (anti-tTG IgA + total IgA) - celiac disease causes fatigue
Autonomic / Cardiovascular - Usually Covered
  • NASA lean test (10-min standing test) - a bedside test for POTS/OI requiring only a blood pressure cuff and watch. Any PCP can perform; no special equipment needed. Documents HR and BP changes at 2, 5, and 10 minutes of standing.[16]
  • 12-lead ECG - rule out cardiac causes of symptoms
  • 24-hour Holter monitor - resting tachycardia, arrhythmias; usually covered with cardiac indication
  • Orthostatic vital signs - lying/sitting/standing BP and HR measurement; can be done in any office
  • Sleep study (PSG) - usually covered when sleep apnea is suspected; important to rule out/treat comorbid sleep apnea

Tier 2: Specialist-Ordered, Often Covered with Referral

These tests typically require specialist referral (infectious disease, rheumatology, neurology, cardiology) and are usually but not always covered. Pre-authorization may be needed.

Immune / Infection Panel
  • EBV panel (VCA IgG + IgM, EA-D antibody, EBNA IgG) - assesses acute vs. past vs. reactivating EBV infection[13]
  • HHV-6 and CMV IgG antibodies - herpesvirus reactivation markers
  • NK cell function panel (cytotoxicity assay, not just cell count) - a functional immune marker; available at specialty labs
  • Lyme disease serology (ELISA + Western blot, CDC two-tier protocol) - standard Lyme testing when exposure history exists
  • DHEA-S, sex hormones (testosterone, estradiol, progesterone) - hormonal contributions to fatigue
  • Morning cortisol or ACTH stimulation test - HPA axis assessment
  • Tilt table test - gold standard for POTS and NMH; requires cardiology or autonomic neurology referral
Neurological / Specialty
  • Brain MRI - rules out MS, lesions, tumors; can reveal white matter changes; covered with neurological indication
  • QSART (quantitative sudomotor axon reflex test) - autonomic small fiber testing; specialty neurology lab
  • Neuropsychological testing - objective cognitive function assessment; sometimes covered under neuropsychology referral
  • 2-day CPET - documents PEM objectively; available at Workwell Foundation (Ripon, CA) and specialist centers; requires prior authorization; insurance coverage inconsistent[23]
  • Heart rate variability (HRV) analysis - autonomic measure; can be done with some wearables or Holter

Tier 3: Out-of-Pocket / Specialized Labs - Not Routinely Covered

These tests are not part of standard clinical panels, may not be available at commercial labs, and are typically paid for out-of-pocket. They are most relevant for patients with specific clinical presentations or who are participating in specialist ME/CFS care.

Out-of-Pocket: Immune / Autoimmune
  • GPCR autoantibodies (beta-2 adrenergic, M3/M4 muscarinic receptor antibodies) - primarily available through Charite Berlin research collaborations or CellTrend GmbH (Germany); guides immunoadsorption candidacy[12]
  • IVIG pre-screening (IgG subclass deficiencies, IVIG candidacy panel) - specialty immunology
  • Cytokine panels (IL-6, IL-8, TNF-alpha, TGF-beta) - research labs; not standardized for clinical use
  • NK cell function (detailed cytotoxicity panels) - specialty immunology labs beyond basic NK count
Out-of-Pocket: Infectious / Tick-Borne
  • IGeneX Labs Lyme testing - uses a broader Western blot panel than CDC standard; detects additional Borrelia species and co-infections (Bartonella, Babesia, Ehrlichia, Anaplasma). Controversial: some physicians recommend in seronegative presentations with tick-bite history; mainstream infectious disease guidance does not endorse over standard two-tier testing. Cost: ~$200-500+ per panel.[73]
  • Bartonella, Babesia testing - available at Galaxy Diagnostics (Bartonella) and specialty labs; not routinely covered
  • EBV early antigen by quantitative PCR - distinguishes active replication from past infection; available at specialty virology labs
  • Enterovirus serology - limited availability; relevant in suspected enteroviral trigger
  • Long COVID blood panels (spike protein assays, microclot detection, PASC biomarker panels) - emerging; available at select research labs
Out-of-Pocket: Metabolic / Mitochondrial
  • RBC magnesium (not serum) - intracellular magnesium; available at specialty labs, often not covered
  • Urinary organic acids - mitochondrial function markers; available at Genova Diagnostics, Great Plains Laboratory
  • Comprehensive amino acid panel - neurotransmitter precursors, protein metabolism
  • Mitochondrial function testing (fibroblast ATP production, Seahorse XF assay) - research settings only; not clinically available
  • Stool microbiome analysis (comprehensive) - Viome, Genova GI Effects, etc.; not covered; guides probiotic strategies[20]
  • Intestinal permeability (lactulose/mannitol ratio) - leaky gut assessment; available at functional medicine labs
Out-of-Pocket: Mast Cell / Autonomic
  • Urine 24-hour histamine + prostaglandin D2 + tryptase - MCAS workup; must be collected during symptomatic period; collection protocol is critical[33]
  • Plasma histamine, serum tryptase - MCAS screening (serum tryptase is sometimes covered if ordered by allergist)
  • Skin punch biopsy (IENFD) - small fiber neuropathy diagnosis; available at neurology centers with skin biopsy capability; coverage inconsistent[17]
  • Cerebral blood flow measurement - reduced cerebral blood flow on standing is one of the better-documented objective abnormalities in ME/CFS, measured by extracranial Doppler during head-up tilt[112]. Available at a small number of specialist autonomic centers, rarely covered, and not part of any ME/CFS diagnostic criteria. SPECT brain imaging is sometimes offered for the same purpose at nuclear medicine centers, but it is not the modality the ME/CFS cerebral blood flow evidence rests on.
A Note on IGeneX and Extended Lyme Testing IGeneX and similar extended tick-borne illness labs use broader assay panels than the CDC two-tier standard and detect additional Borrelia genospecies. Some ME/CFS patients, particularly those with a history of tick exposure or who live in high-Lyme areas, pursue these tests when standard Lyme testing is negative. The evidence base for clinical decision-making based on IGeneX results alone is limited, and mainstream infectious disease organizations (IDSA) do not endorse extended Lyme testing over standard protocols. These tests can be useful as part of a full clinical evaluation but should not drive long-term antibiotic treatment without strong corroborating clinical evidence - the RCT evidence shows prolonged antibiotics do not benefit PTLDS patients and carry significant risks.[53,73]