orthostatic intolerance


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orthostatic intolerance

an abnormal response to standing upright that results from decreased blood pressure and inadequate blood flow to the brain, characterized by a variety of symptoms, including lightheadedness, palpitations, tremulousness, visual disturbances, and syncope. It occurs in both acute and chronic forms and is frequently seen as a transient condition in space travelers returning from microgravity. The cause is unknown but may be related to abnormalities in the autonomic regulation of cardiovascular function.

orthostatic intolerance

A condition (OMIM:604715) characterised by lightheadedness, fatigue, altered mentation, syncope and tachycardia upon assuming an upright position, and markedly elevated serum norepinephrine. 

Molecular pathology
Defects in SLC6A2, which encodes a member of the sodium:neurotransmitter symporter that regulates norepinephrine homeostasis, are a cause of orthostatic intolerance.

or·tho·stat·ic in·tol·er·ance

(ōr'thō-stat'ik in-tol'ĕr-ăns)
Decreased venous return in the upright position typically experienced by astronauts after returning to an environment subject to gravity.

orthostatic intolerance

Loss of consciousness, near fainting, or light-headedness occurring when a person stands up from a seated or resting position. It is caused by insufficient blood flow to the brain, typically brought on by inability to raise blood pressure during changes in posture.
References in periodicals archive ?
They were healthy children without syncope, chest tightness, headache, or other symptoms of orthostatic intolerance, as demonstrated by a normal medical history, physical examination, and laboratory findings.
Postexertional malaise * * Unrefreshing sleep * Plus at least one of the two following manifestations (chronic, severe): * Cognitive impairment * * Orthostatic intolerance Source: Institute of Medicine.
There are several types of orthostatic intolerance.
The clinical scenario is that of orthostatic intolerance following a period of very rapid growth.
It was three years and 60 different tests before he was finally diagnosed with orthostatic intolerance, a malfunction of the nervous system which causes a delay in adequate blood supply to the " brain.
He suffered from orthostatic intolerance, a malfunction of the nervous system which causes a delay in adequate blood supply to the brain.
35) pointed out, "Research is needed to validate the use of dangling in clinical practice, to test different dangling methods, to determine normal and abnormal responses, to predict patients likely to have orthostatic intolerance, and to test methods to promote orthostatic tolerance.
3 bpm, with 18 of 31 (58%) patients meeting criteria for orthostatic intolerance (an increase of more than 30 bpm).
Page had to hand over his yellow skivvy in late 2006 because of a diagnosis of orthostatic intolerance, a nervous system disorder.
Orthostatic intolerance has been reported in ultra-marathon runners due to volume depletion; (9) however, in light of the relatively short time to onset in our patient, and the lack of orthostasis after recovery, we did not suspect that this mechanism was at work.
In a video-recorded statement, Greg Page said a little-understood disorder called orthostatic intolerance had left him debilitated.