A study of 52 patients with POTS between the ages of 14 and 29 years showed decreased BMI in patients with reduced peripheral blood flow.18,19 Patients with POTS who have reduced peripheral blood flow also have an abnormally high level of angiotensin II, which is correlated with lower BMI in these patients.18,19 Increased angiotensin II within the CNS can produce sympatho-excitation, which is a major factor in the subgroup of hyperadrenergic POTS.19 This evidence concerns the gene AGT and postural orthostatic tachycardia syndrome.