This study sought to estimate the co-occurrence rate of Ehlers-Danlos Syndrome (EDS), Fibromyalgia (FM), and Mast Cell Activation Syndrome (MCAS) in postural orthostatic tachycardia syndrome (POTS) patients with and without Endometriosis.

POTS often co-occurs with EDS, FM, and MCAS. Recent studies have questioned if POTS and endometriosis, both chronic illnesses primarily affecting women, are associated with one another. It is also unclear whether the co-occurrence of these chronic conditions differs between female patients with POTS with and without endometriosis. 

In a retrospective analysis, we reviewed medical records for 1,322 patients with POTS who presented to our autonomic center from 2018 to 2024. POTS was defined by symptoms of orthostatic intolerance accompanied by a heart rate increase of ≥30 beats per minute within the first 10 minutes of head-up tilt table testing. Endometriosis diagnoses were determined using surgical pathology when available or clinical documentation. EDS, FM, and MCAS diagnoses were determined using ICD codes.

Among 1,322 female patients with POTS, 229 (17.3%) had a diagnosis of endometriosis, a prevalence significantly higher than the prevalence of 10% observed in the general female population (p<0.001). EDS and MCAS were significantly more prevalent in female POTS patients with endometriosis compared to those without endometriosis (33.2% vs 13.1%, p < 0.001; 18.8% vs 3.1%, p < 0.001, respectively). FM prevalence did not differ significantly between groups (14.0% vs 9.2%, p = 0.21).

Amongst female patients with POTS, those with endometriosis have higher co-occurrence of EDS and MCAS than those without endometriosis, while FM co-occurrence is similar. These results suggest a possible shared pathophysiology amongst these chronic conditions. Future studies should investigate the underlying mechanisms linking these conditions and evaluate whether targeted screening or management strategies may improve patient outcomes.