Sympathetic Nervous System Response to Orthostatic Stress in Female Patients with Rheumatoid Arthritis

16 females, comprising 8 patients with rheumatoid arthritis (RA) and 8 matched healthy controls

Orthostatic stress testing (sequence of stabilization period in supine position, legs-up position, orthostasis, and supine position)

Matched healthy controls undergoing the same orthostatic stress testing

Sympathoneural and adrenomedullary responses to orthostasis, measured by plasma levels of epinephrine (EPI), norepinephrine (NE), neuropeptide Y (NPY), and heart rate variability (HRV)surrogate