1 causes
1.1 hypovolemia
1.2 diseases
1.3 medication
1.4 other factors
causes
orthostatic hypotension caused gravity-induced blood pooling in lower extremities, in turn compromises venous return, resulting in decreased cardiac output , subsequent lowering of arterial pressure. example, changing lying position standing loses 700 ml of blood thorax, decrease in systolic , diastolic blood pressures. overall effect insufficient blood perfusion in upper part of body.
still, blood pressure not fall much, because triggers vasoconstriction (baroreceptor reflex), pressing blood body again. (often, mechanism exaggerated , why diastolic blood pressure bit higher when person standing up, compared person in horizontal position.) therefore, secondary factor causes greater normal fall in blood pressure required. such factors include low blood volume, diseases, , medications.
hypovolemia
orthostatic hypotension may caused low blood volume, resulting bleeding, excessive use of diuretics, vasodilators, or other types of drugs, dehydration, or prolonged bed rest(immobility); occurring in people anemia.
diseases
the disorder may associated addison s disease, atherosclerosis (build-up of fatty deposits in arteries), diabetes, pheochromocytoma, porphyria, , neurological disorders, including multiple system atrophy , other forms of dysautonomia. associated ehlers–danlos syndrome , anorexia nervosa. present in many patients parkinson s disease resulting sympathetic denervation of heart or side-effect of dopaminomimetic therapy. leads fainting unless person has developed true autonomic failure or has unrelated heart problem.
another disease, dopamine beta hydroxylase deficiency, thought underdiagnosed, causes loss of sympathetic noradrenergic function , characterized low or extremely low levels of norepinephrine, excess of dopamine.
quadriplegics , paraplegics might experience these symptoms due multiple systems inability maintain normal blood pressure , blood flow upper part of body.
medication
tetrahydrocannabinol
orthostatic hypotension can side-effect of antidepressants, such tricyclics or monoamine oxidase inhibitors (maois). marijuana , tetrahydrocannabinol can on occasion produce marked orthostatic hypotension. orthostatic hypotension can side effect of alpha-1 blockers (alpha1 adrenergic blocking agents). alpha1 blockers inhibit vasoconstriction initiated baroreceptor reflex upon postural change , subsequent drop in pressure.
other factors
patients prone orthostatic hypotension elderly, post partum mothers, , having been on bedrest. people suffering anorexia nervosa , bulimia nervosa suffer orthostatic hypotension common side-effect. consuming alcohol may lead orthostatic hypotension due dehydrating effects.
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