xchocoholic
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This doctor has a familiar view of OH but IMHO is worth reviewing because he actually goes into some details than I haven't seen before. He even looks for some causes ... I only copied in a tiny bit of this article. He has a section called "Laboratory TESTS for orthostatic hyptension" that I want to look at further. tc ... x
http://www.dizziness-and-balance.com/disorders/medical/orthostatic.html
http://www.dizziness-and-balance.com/disorders/medical/orthostatic.html
ORTHOSTATIC HYPOTENSION
Timothy C. Hain, MD.Page last modified: January 21, 2012
Translations: Belorussion
Orthostasis means upright posture, and hypotension means low blood pressure. Thus, orthostatic hypotension consists of symptoms of dizziness, faintness or lightheadedness which appear only on standing, and which are caused by low blood pressure. Only rarely is spinning vertigo caused by orthostasis.
Symptoms that often accompany orthostatic hypotension include chest pain, trouble holding the urine, impotence, and dry skin from loss of sweating. Fainting (syncope) is covered in another page.
How common is orthostatic hypotension ?
According to Wu et al (2008), symptoms of dizziness provoked by standing ranges from 4.4% (young) to 5.8% (>=70). Thus orthostatic dizziness is common and much more frequent than dizziness due to inner ear disturbances.
What Causes Orthostatic Hypotension ?
Blood pressure is maintained by a combination of several things. The heart is the central pump, and a weak or irregular heart can cause orthostatic hypotension. Conditions such as arrhythmia, heart failure, deconditioning, and pregnancy are examples where the heart may not be up to the task of providing an adequate blood pressure.
The heart pumps blood, and if there is too little blood volume (anemia, dehydration, dialysis), the pressure drops. The blood vessels in the body also can squeeze (constrict) to raise blood pressure, and if this action is paralyzed, blood pressure may fall. Numerous medications affect blood vessels including most of the medications used for blood pressure, and many of the medications used in psychiatry and for anginal heart pain. Heat, such as a hot shower or from a fever can also dilate blood vessels and cause orthostasis. The nervous system senses and responds to regulate blood pressure. If something is wrong in this control system, blood pressure may fluctuate.
Blood pressure is usually lowered (in persons with orthostasis) by upright posture, food, infection, hyperventilation, hot weather, and lifting of heavy objects. General anesthesia may be unusually dangerous due to blood pressure fluctuations (Bevan et al, 1979).
Vestibular disorders may interact with blood pressure and heart rate control. The vestibular system is one source of information about uprightness (the otoliths), there are some effects of vestibular stimulation on the heart (Radtke, 1992), and there are some patients who have a combination of autonomic and vestibular symptoms.
Neurological disorders can also be caused by orthostasis. This usually takes the form of a transient ischemic attack (TIA) precipitated by a blood pressure drop (Brozman et al, 2002).
Diagnosis of Orthostatic Hypotension
Syndromes with orthostatic dizziness or lightheadedness, not associated with low blood pressure include:
Syndromes with orthostatic hypotension that may be diagnosed include:
- Positional orthostatic tachycardia (POT) syndrome. Here, the pulse races on standing. See below for more information.
- Low CSF pressure syndrome
- Primary orthostatic tremor
- Positional vertigo (i.e. BPPV)
The diagnosis of orthostasis is made by finding that the systolic/diastolic blood pressure drops at least 25/10 mm mercury on going from lying to standing. After measuring the supine blood pressure, it is recommended that one should have the subject stand for 2 minutes (if tolerated) before measuring the upright blood pressure (Tarazi and Fouad, 1983).
- Cardiogenic (heart related) orthostatic hypotension. In this instance the heart doesn't respond adequately to demands for greater pumping and blood pressure drops. Conditions such as arrhythmia, heart failure, deconditioning, and pregnancy are examples.
- Low blood volume (e.g. anemia, dehydration, dialysis)
- Medication related (usually too high doses of blood pressure medications or medications for depression)
- Primary adrenal insufficiency. Persons with primary adrenal insufficiency usually also have symptoms of glucocorticoid (cortisone) deficiency. The skin may be dark, serum potassium high, and there may be associated hypothyroidism, diabetes, and vitiligo (Salvatori, 2005).
- Neurogenic orthostatic hypotension
- Sensory neuropathies (diabetes, alcohol, syphilis, Holmes-Adie syndrome, carotid sinus obliteration by endarterectomy, Riley-Day syndrome)
- Central types:
- MSA - multiple system atrophy or Shy-Drager, Parkinson's, dementia with Lewy bodies. Orthostatic hypotension is nearly universal in MSA, present in about 50% of patients with dementia with Lewy bodies (Akaogi et al, 2009), and in 5-50% of patients with Parkinson's. (Thaisetthawatkul et al, 2004; Akaogi et al, 2009). However, since Parkinsonism is by far the most common disorder, there may be as many patients with orthostatic hypotension and Parkinson's disease as any of the former. Patients with MSA have intact sympathetic noradrenergic innervation.
- Medullary strokes or injuries (rare)
- Wernickes syndrome (rare, related to thiamine deficiency)
- Output types:
- Peripheral neuropathy, especially diabetes and amyloidosis
- Spinal cord lesions
- PAF - pure autonomic failure or idiopathic orthostatic hypotension. These patients have loss of cardiac sympathetic neurons, and in particular have loss of sympathetic noradrenergic innervation.
- Parkinson's disease(post-ganglionic sympathetic denervation). These patients also have loss of cardiac sympathetic neurons.
- Dopamine beta-hydroxylase deficiency (hereditary, very rare -- has very high serum dopamine, often ptosis (droopy eyes) and hyperextensible joints. Prolactin may be high)
- Unknown type
- Orthostatic intolerance in chronic fatigue syndrome (this mainly seems to be a syndrome of adolescents)
- Orthostatic intolerance associated with basilar migraine
- Delayed orthostatic hypotension. Possibly due to fatigue of autonomic system over 3-20 minutes.