Postural orthostatic tachycardia syndrome

Postural orthostatic tachycardia syndrome (POTS) is a condition where a patient's heart rate substantially increases upon sitting or standing. It is a form of orthostatic intolerance (OI).

POTS in ME/CFS
POTS is sometimes diagnosed in ME/CFS patients.

Diagnosis of ME/CFS
OI is very often present in ME/CFS. The proposed SEID criteria has OI as a symptom but it is not necessary for a diagnosis as it is not always present. If the patient does not have OI they would have to have Cognitive Impairment (Cognitive dysfunction) to meet SEID criteria.