Measures heart rate lying down vs standing. An increase of more than 30 bpm suggests POTS. Recommended by the US ME/CFS Clinician Coalition as a mandatory test.

Tests for beta-2, M3 and M4 autoantibodies. Developed by Scheibenbogen/Charité. Affects approximately 20-30% of patients. Only available through CellTrend laboratory in Luckenwalde, Germany.

Gold standard for diagnosing POTS and orthostatic hypotension. Patient is tilted from lying to standing position while heart rate and blood pressure are continuously monitored.

Measures actual blood volume. ME/CFS patients often have significantly reduced blood volume despite normal haematocrit – a finding standard blood tests miss entirely.

Measures exhaled CO2 lying down vs standing. Reveals hyperventilation and orthostatic hypocapnia – a common but overlooked finding in ME/CFS.

Autoantibodies that block folate transport into the brain. Blood folate levels appear normal. Particularly elevated in EBV-triggered ME/CFS cases. Causes neuroinflammation and mitochondrial damage in the CNS.

Measures only the active B12 fraction actually available to cells. Total B12 can appear normal while Holo-TC is low – the classic diagnostic trap that misleads both patients and doctors.

Elevated MMA confirms functional B12 deficiency at cellular level even when blood levels appear normal. Key decision point: low Holo-TC + high MMA = functional deficiency very likely.

Elevated homocysteine indicates problems in both B12 and folate metabolism. Helps narrow down which deficiency is driving the problem.

Measures folate stored in red blood cells – a long-term marker more accurate than serum folate for assessing cellular folate availability.

Genetic test. Impairs conversion of B12 and folate into their active forms. Relevant when homocysteine is elevated or family history exists. One-time test, result permanently valid.

Detects pernicious anaemia – an autoimmune condition preventing B12 absorption in the gut regardless of dietary intake.

Full panel mandatory. Early Antigen IgG (EA-IgG) specifically indicates active reactivation. Ordering only VCA IgG misses active reactivation entirely.

NOT NK cell count (often normal) but killing activity. The most consistent finding in ME/CFS research over 30 years. Must be analysed within 24 hours of blood draw at room temperature – specialist laboratory essential.

Low avidity indicates recent reactivation rather than old infection. Standard HHV-6 IgG alone cannot distinguish these. Avidity test is the critical addition.

Tests for mast cell activation syndrome (MCAS) – a common comorbidity in ME/CFS. At least two body systems must be affected to meet diagnostic criteria.

Cortisol measured at waking, noon, 4pm and bedtime. A flat cortisol curve is characteristic of ME/CFS. Critically: single morning blood cortisol does NOT show this pattern.

Small punch biopsy of the skin measuring density of small nerve fibres. Frequently reduced in ME/CFS. Provides objective evidence of neurological damage.

Measures blood flow velocity in cerebral arteries lying down vs standing. Can objectively demonstrate cerebral hypoperfusion as a cause of brain fog.

Gold standard for objectifying PEM. Two maximal exercise tests 24 hours apart. ME/CFS patients show significant decline on day 2 – a pattern not seen in any other chronic illness. Documents disability objectively.

Measures lactate build-up at low exercise levels. ME/CFS patients switch to anaerobic metabolism much earlier than healthy controls.