Orthostatic hypotension is an independent predictor of mortality and the cause of significant morbidity associated with falls.
A common problem in frail older people. Orthostatic hypotension-related hospitalisations increase markedly with age.
Common causes include drugs (e.g., alpha-blockers, including tamsulosin [used for treating conditions such as benign prostatic hypertrophy], central sympatholytics, including tizanidine [used as a muscle relaxant], and diuretics), diseases causing peripheral neuropathy (e.g., diabetes mellitus), Parkinson's disease, and dementia with Lewy bodies.
Primary neurodegenerative disorders of the autonomic nervous system (pure autonomic failure, and multiple system atrophy or Shy-Drager syndrome) are less common, but cause severe orthostatic hypotension.
Acute or subacute onset should suggest an autoimmune or paraneoplastic disorder.
Treatment consists of addressing any underlying pathology, when possible, followed by discontinuing or reducing the dose of aggravating drugs, and non-pharmacological countermeasures (e.g., liberalisation of salt intake, use of abdominal binders or compression stockings). Volume expansion (using mineralocorticoid therapy), short-acting vasopressors, or noradrenaline (norepinephrine) precursor therapy with droxidopa are adjunctive therapies when non-pharmacological measures are insufficient.
Orthostatic hypotension is defined as a fall in systolic blood pressure of at least 20 mmHg (at least 30 mmHg in patients with hypertension) and/or a fall in diastolic blood pressure of at least 10 mmHg within 3 minutes of standing. When orthostatic hypotension has an underlying neurogenic cause (e.g., peripheral neuropathy) it is associated with a blunted increase in heart rate, typically less than 15 bpm. Orthostatic hypotension becomes clinically significant if it is accompanied by symptoms of cerebral hypoperfusion, which can lead to syncope and falls. Orthostatic hypotension is associated with increased risk of dementia and cardiovascular disease, and is an independent risk factor for all-cause mortality. This topic concentrates on orthostatic hypotension caused by autonomic problems.
History and exam
Key diagnostic factors
- presence of risk factors
- postural light-headedness, syncope, and other symptoms of cerebral hypoperfusion
Other diagnostic factors
- parkinsonian features
- cerebellar ataxia
- weight loss
- resting tachycardia or impaired heart rate variation
- abnormal gastrointestinal motility
- erectile dysfunction and lack of ejaculation
- anhidrosis, heat intolerance, dry skin, focal hyperhidrosis
- urinary frequency, urgency, nocturia
- older adult age
- frailty and physical deconditioning
- medications that impair sympathetic tone
- volume depletion/anaemia
- autonomic neuropathy (e.g., diabetes mellitus)
- Parkinson's disease
- dementia with Lewy bodies
- multiple system atrophy
1st investigations to order
- posture test
Investigations to consider
- tilt-table test
- plasma noradrenaline (norepinephrine)
- deep breathing
- Valsalva manoeuvre
- nerve conduction studies and electromyogram (EMG)
- quantitative sudomotor axon reflex test (QSART)
- heart rate variability
- 24-hour blood pressure monitoring
- autoimmune antibodies
- chest CT
- serum and urine electrophoresis
- fat-pad biopsy
- genetic testing
- Neurally mediated (vasovagal) syncope
- Non-specific falls in older people
- Guidelines on the diagnosis and management of syncope
- Consensus statement on the definition of neurogenic supine hypertension
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