The cause of POTS is unknown. For many years, such patients were felt to have deconditioning and were encouraged to pursue a more vigorous exercise regimen. However, recently it has become clear that many individuals with these symptoms have a more serious problem than mere deconditioning. The onset is often predated by a recent viral infection.
Patients can undergo extensive clinical evaluation without identification of a specific abnormality, and therefore most patients remained undiagnosed. These difficulties are compounded by the heterogeneity of disease states in patients with orthostatic symptoms, spontaneous fluctuations in disease severity, and no uniformity in nomenclature of disease classification. Another problem in the diagnosis is its overlap with other conditions such as:
Improving characterization of the underlying circulatory responses may lead to a clarification of some of those issues, and will facilitate the discovery of the pathophysiology of this disorder.