Diseases & Conditions


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Hypotension, Orthostatic


Synonyms of Hypotension, Orthostatic
  • Postural Hypotension

Disorder Subdivisions



    General Discussion
    Orthostatic hypotension (OH) describes an extreme drop in blood pressure that may occur when a person stands up suddenly and the blood pools in the blood vessels of the legs. Because of this pooling, the amount of blood carried back to the heart by the veins is decreased. Subsequently, less blood is pumped out from the heart, resulting in a sudden drop in blood pressure. By definition, the drop in blood pressure must be greater than 20 mm of mercury during contraction of the heart muscles (systole) and more than 10 mm of mercury during expansion of the heart muscles (diastole). Among children and teenagers, short-lived episodes of OH are normal and not uncommon. Episodes among the elderly are always to be taken seriously.

    Normally, specialized cells in the body (baroreceptors) quickly respond to changes in blood pressure. These baroreceptors then activate the autonomic nervous system to increase, via reflex action, levels of catecholamines (e.g. epinephrine, norepinephrine) in the body. Increased catecholamine levels rapidly restore the blood pressure. A defect in this spontaneous response (reflex), prevents the heart rate and blood pressure from rising adequately and orthostatic hypotension results. Fainting and falling are the usual consequences.

    Some clinical neurologists prefer to focus on three primary syndromes of the failure or breakdown of the autonomic nervous system. These are:

    Acute or subacute idiopathic pandysautonomia (ASIP) refers to the breakdown of the autonomic nervous system (control of breathing, blood circulation, pain, taste, etc.) from unknown causes.

    Pure autonomic failure (PAF) is sometimes defined as the presence of orthostatic hypotension (without an identifiable cause such as medically prescribed drugs) without evidence of any other neurological problem(s). This term, according to an international consensus committee, replaces Bradbury-Egglestone syndrome, idiopathic orthostatic hypotension, and progressive autonomic failure.

    Organizations related to Hypotension, Orthostatic
    • Autonomic Dysfunction Center
      Vanderbilt University Medical Center
      Nashville TN 37232-2195
      Phone #: 615-343-6499
      800 #: --
      e-mail: david.robertson@vanderbilt.edu
      Home page: http://www.mc.vanderbilt.edu/gcrc/adc
    • National Dysautonomia Research Foundation
      PO Box 301
      Red Wing MN 55066-0102
      Phone #: 651-267-0525
      800 #: --
      e-mail: ndrf@ndrf.org
      Home page: http://www.ndrf.org
    • National Institute of Neurological Disorders and Stroke (NINDS)
      31 Center Drive
      Bethesda MD 20892-2540
      Phone #: 301-496-5751
      800 #: 800-352-9424
      e-mail: braininfo@ninds.nih.gov
      Home page: http://www.ninds.nih.gov/



    For a Complete Report

    This is an abstract of a report from the National Organization for Rare Disorders, Inc. ? (NORD). A copy of the complete report can be obtained for a small fee by visiting the NORD website. The complete report contains additional information including symptoms, causes, affected population, related disorders, standard and investigational treatments (if available), and references from medical literature. For a full-text version of this topic, see http://www.rarediseases.org/search/rdblist.html