Abstract-Postural tachycardia syndrome (POTS) is a disabling condition that commonly affects otherwise normal young females. Because these patients can present with a flushing disorder, we hypothesized that mast cell activation (MCA) can contribute to its pathogenesis. Here we describe POTS patients with MCA (MCAϩPOTS), diagnosed by episodes of flushing and abnormal increases in urine methylhistamine, and compared them to POTS patients with episodic flushing but normal urine methylhistamine and to normal healthy age-matched female controls. MCAϩPOTS patients were characterized by episodes of flushing, shortness of breath, headache, lightheadedness, excessive diuresis, and gastrointestinal symptoms such as diarrhea, nausea, and vomiting. Triggering events include long-term standing, exercise, premenstrual cycle, meals, and sexual intercourse. In addition, patients were disabled by orthostatic intolerance and a characteristic hyperadrenergic response to posture, with orthostatic tachycardia (from 79Ϯ4 to 114Ϯ6 bpm), increased systolic blood pressure on standing (from 117Ϯ5 to 126Ϯ7 mm Hg versus no change in POTS controls), increased systolic blood pressure at the end of phase II of the Valsalva maneuver (157Ϯ12 versus 117Ϯ9 in normal controls and 119Ϯ7 mm Hg in POTS; Pϭ0.048), and an exaggerated phase IV blood pressure overshoot (50Ϯ10 versus 17Ϯ3 mm Hg in normal controls; PϽ0.05). In conclusion, MCA should be considered in patients with POTS presenting with flushing. These patients often present with a typical hyperadrenergic response, but ␤-blockers should be used with great caution, if at all, and treatment directed against mast cell mediators may be required.

No abstract

No abstract