Orthostatic hypotension

Definition

• A decrease in blood pressure when changing from sitting to standing of more than 20mmHg systolic or 10mmHg diastolic

Etiologies

• Primary autonomic failure (neurodegenerative diseases) (30%)
  • Parkinson disease
  • Dementia with Lewy bodies
  • Multiple system atrophy
  • Pure autonomic failure
• Secondary autonomic failure (neuropathies) (35%)
  • Small fiber neuropathies
    • Diabetes (most common cause)
    • Amyloidosis
    • Sjogren syndrome
    • Sarcoidosis
    • Other connective tissue disorders
    • Renal failure
    • Vitamin B12 deficiency
    • Toxins
    • Infections: syphilis, Lyme, HIV, Chagas
    • Porphyria
  • Autoimmune autonomic gangionopathy
  • Paraneoplastic autonomic neuropathy: small cell lung cancer
  • Familial dysautonomic (Rile Day syndrome)
• No generalized autonomic dysfunction (40%)
  • Volume depletion
  • Medications and drugs: alcohol, alpha blockers (terazosin), SSRIs/TCAs/MAOIs/trazodone, antihypertensives, antiparkinsonism drugs, antipsychotics, beta-blockers, diuretics, muscle relaxants, opioids, phosphodiesterase inhibitors, sedatives, vasodilators
    • Antidepressants are major overlooked cause
  • Aging (decreased baroreceptor sensitivity)
  • Other
    • Aortic stenosis
    • Pericarditis/myocarditis
    • Arrhythmias
• About 1/3 of patients will have no identifiable cause for chronic orthostatic hypotension

Differential Diagnosis

• Postprandial hypotension
• Reflex syncope
• Postural tachycardia syndrome and chronic orthostatic intolerance (COI)

Clinical Manifestations

• History
  • Any recent volume loss?
  • Rule out CHF, malignancy, diabetes, and alcohol abuse
  • Evaluate for parkinsonism, ataxia, peripheral neuropathy or dysautonomia
    • Abnormal pupillary response
    • Chronic constipation
    • Erectile dysfunction
  • Rule out postprandial hypotension
• Physical exam
  • Lying 5min, then measure supine BP
  • Standing 1-5min, then measure standing BP
  • Change at 1min most associated with falls
  • Isolated increase in heart rate of more than 30bpm suggests postural tachycardia syndrome (not orthostatic hypotension)

Investigations

• Laboratory
  • CBC
  • Lytes, creatinine for renal disease, dehydration
  • Glucose, A1c for diabetes control
  • Consider syphilis screening, SPEP, or other investigations for polyneuropathy
• Other
  • EKG
  • Consider EMG studies if abnormal neurological exam

Management

• Review medications for offenders (including antidepressants)