Why do patients with orthostatic hypotension have diurnal variation in blood pressure?
Many patients with orthostatic hypotension have supine hypertension, even before they are treated with fludrocortisone or other medications.
The reason for supine hypertension remains to be determined; however, it seems that baroreflex dysfunction may play a role.
Prolonged supine position at night may lead to natriuresis and diuresis and eventually contracture of intravascular volume.
These events cause the orthostatic hypotension to become more severe in the morning.
