What Actually Causes POTS? A Mechanistic Reading of Postural Orthostatic Tachycardia Syndrome — Tests that help stratify

The tilt-table test confirms the POTS diagnosis. It does not stratify the mechanism. The following testing provides mechanism-level information: For Pathway 1 (post-viral): detailed history of any infection in the 6 to 18 months preceding POTS onset; serum NAD+ if accessible; the CD38-NAD+ pattern can be inferred from the clinical picture without formal testing if the post-viral signature is clear; inflammatory markers, particularly hsCRP, ferritin (as acute-phase reactant), and IL-6 if available. For Pathway 2 (gut-driven): heart rate variability assessment (consumer wearables provide adequate data); comprehensive stool panel (GI-MAP or equivalent); organic acids urine test for the broader inflammatory and microbial picture. For Pathway 3 (connective tissue): Beighton score for joint hypermobility; skin examination for the elasticity and stretchiness findings of hEDS; family history of hypermobility or POTS; echocardiogram if mitral valve prolapse or aortic root dilation is suspected; geneticist referral for the rare cases where the connective tissue variant requires formal classification. For Pathway 4 (deconditioning): detailed activity history including any period of bed rest, immobilization, or prolonged low activity in the 6 to 12 months preceding POTS onset; cardiopulmonary exercise testing if accessible. The full mechanistic stratification rarely requires all of this te