Management of Postural Orthostatic Tachycardia Syndrome and Mast Cell Activation Syndrome

Diagnostic Approach

The American College of Cardiology recommends performing formal orthostatic vital signs to document heart rate increase ≥30 bpm (or ≥120 bpm absolute) within 10 minutes of standing without orthostatic hypotension for POTS diagnosis 2
The American Gastroenterological Association suggests obtaining serum tryptase levels, collecting baseline tryptase and repeating 1-4 hours following a symptomatic flare, with a diagnosis requiring an increase of 20% above baseline plus 2 ng/mL for MCAS diagnosis 5, 6

The American College of Allergy, Asthma, and Immunology recommends continuing and optimizing antihistamine therapy with the combination of H1 and H2 antihistamines as first-line prophylactic treatment for MCAS, with H2 blockers specifically beneficial for gastrointestinal symptoms and helping H1 antihistamines attenuate cardiovascular symptoms 1
The American Heart Association suggests increasing salt and fluid intake aggressively, ensuring intake is truly adequate (typically 2-3 liters of fluid and 6-10 grams of sodium daily), and adding compression garments for POTS symptoms 2, 3
The American College of Cardiology recommends considering midodrine 2.5-10 mg three times daily if conservative measures fail to adequately control lightheadedness and fainting for POTS symptoms 2

The Clinical Gastroenterology and Hepatology association notes that POTS and MCAS frequently coexist, with studies showing 31-42% of POTS patients meeting criteria for MCAS, and dual therapy targeting both conditions is often necessary 3