[Does constitutional hypotension exist?].

Orthostatic hypotension is frequently related to severe insufficiency of the autonomic nervous system associated with neuropathy or systemic disease like diabetes. Inversely, pre-syncopal orthostatic symptoms associated with mild drop in orthostatic blood pressure is quite often a reason to seek medical care, but is relatively unrecognized in the literature. Recently a syndrome of mild orthostatic intolerance has been defined, and seem to be quite common among young subjects, characterized by frequent orthostatic presyncopal symptoms associated with orthostatic tachycardia and high plasma catecholamines levels. In the paper, we will review different causes of orthostatic hypotension, and mention some physiopathological mechanisms linked to renal sodium handling. In particular, alterations in renal proximal segmental handling of sodium might generate and play a pathophysiological role in maintenance of the orthostatic hypotension. Finally, we will evoke some therapeutical aspects.