Reversible postural orthostatic tachycardia syndrome

Table 1 Differentiating partial dysautonomic and hyperadrenergic forms

	Partial dysautonomia	Hyperadrenergic form
Frequency	Most common primary form	Less common primary form
Mechanism	Inability of peripheral vessels to constrict	Tachycardia due to elevated catecholamine
Onset	Abrupt	Gradual
Pathophysiology	Autoimmune mediated	Familial–single point mutation
Investigation	Serum acetylcholine receptor antibodies	Standing catecholamine level