Why am I experiencing hypotension?

Why Is My Blood Pressure Low?

Your blood pressure is likely low due to one or more of the following common causes: medications (especially antihypertensives, diuretics, or vasodilators), volume depletion (dehydration, bleeding, excessive diuresis), autonomic nervous system dysfunction (from conditions like diabetes, Parkinson's disease, or aging), or cardiac causes (heart failure, valvular disease). 1

Immediate Assessment Required

You need to determine whether this is an acute emergency or a chronic condition:

• If systolic BP <80 mmHg with symptoms (confusion, chest pain, severe dizziness, shortness of breath), this requires immediate medical attention as it indicates critical hypoperfusion 1
• Check for signs of shock: cold/clammy skin, rapid weak pulse, altered mental status, decreased urine output 1
• Measure BP in both lying and standing positions after 5 minutes of rest, then at 1 and 3 minutes after standing to assess for orthostatic hypotension (drop ≥20 mmHg systolic or ≥10 mmHg diastolic) 2, 3

Most Common Causes to Investigate

1. Medication-Related (Most Frequent Cause)

• Antihypertensive medications are the leading cause, especially when multiple agents are used 1, 2
• Diuretics cause volume depletion and electrolyte abnormalities 1, 3
• Vasodilators (nitrates, calcium channel blockers) directly reduce vascular tone 3
• Alpha-blockers, beta-blockers, ACE inhibitors all impair compensatory mechanisms 2, 3
• Other culprits: antipsychotics, tricyclic antidepressants, antihistamines, narcotics, anticonvulsants 2

Action: Review ALL medications with your physician; nearly half of hypotension cases in older adults are medication-related 2

2. Volume Depletion

• Dehydration from inadequate fluid intake, fever, or excessive sweating 1
• Hemorrhage (gastrointestinal bleeding, trauma) 1
• Excessive diuresis from overuse of diuretics or uncontrolled diabetes 1
• Diarrhea and vomiting causing fluid losses 1

Action: Assess hydration status, recent fluid losses, and urine output 1

3. Autonomic Nervous System Dysfunction

This is particularly important if you have:

• Diabetes mellitus causing autonomic neuropathy 2, 3
• Parkinson's disease or related disorders (multiple system atrophy, Lewy body dementia) 2, 3
• Advanced age (prevalence 7% in men >70 years, up to 33% in hospitalized elderly) 2, 3
• Spinal cord injury or amyloidosis 2, 3

Key feature: Neurogenic orthostatic hypotension shows a blunted heart rate response (<10 bpm increase) when standing, whereas volume depletion shows preserved or increased heart rate 3, 4

4. Cardiac Causes

• Heart failure (especially advanced stages) with reduced cardiac output 1
• Valvular dysfunction impairing cardiac performance 1
• Cardiogenic shock (systolic BP <90 mmHg with cardiac index <1.8 L/min/m²) 1
• Right ventricular infarction presenting with high jugular venous pressure, bradycardia, and hypotension 1

5. Endocrine Causes

• Adrenal insufficiency (Addison's disease) with low cortisol and aldosterone 5
• Hypoaldosteronism causing low sodium and high potassium 5
• Hypothyroidism reducing cardiac output and vascular tone 5

Age-Related Considerations

If you are older, multiple mechanisms predispose you to hypotension:

• Reduced baroreceptor sensitivity (declines ~1% per year after age 40) 2, 3
• Arterial stiffness causing exaggerated BP variability 2, 3
• Impaired compensatory vasoconstriction and reduced heart rate response 2, 3
• Diminished thirst sensation leading to chronic mild dehydration 2
• Polypharmacy with cumulative medication effects 2

Special Patterns to Recognize

Postprandial Hypotension

• BP drops shortly after meals, common in elderly 2
• Exacerbated by antihypertensive and diabetic medications 2
• Managed by eating smaller meals, reducing carbohydrates, avoiding alcohol with meals 2

Initial Orthostatic Hypotension

• BP drops >40 mmHg systolic within 0-15 seconds of standing 2, 3
• Causes brief lightheadedness immediately upon standing 2
• BP rapidly normalizes within 40 seconds 3

Delayed Orthostatic Hypotension

• BP decline occurs after >3 minutes of standing 3
• Progressive decrease rather than abrupt fall 3
• Common in Parkinsonism, diabetes, and elderly with stiff hearts 3

Critical Pitfall to Avoid

Pseudohypertension from rigid calcified arteries can lead to inadvertent overdosing with antihypertensives, causing symptomatic hypotension despite apparently elevated office readings 2, 3. Suspect this when:

• You develop orthostatic symptoms despite "uncontrolled" BP readings 2
• Osler sign is positive (radial artery remains palpable when BP cuff inflated above systolic pressure) 2

Prognostic Significance

Orthostatic hypotension is associated with:

• 64% increase in age-adjusted mortality compared to controls 2, 3
• Increased falls and fractures, especially backward falls 3
• Increased cardiovascular events and all-cause mortality 4
• Up to 50% increase in relative risk of all-cause mortality 4

Next Steps

1. Confirm the diagnosis: Measure BP supine after 5 minutes rest, then at 1 and 3 minutes standing 2, 4
2. Review ALL medications with your physician for potential culprits 2
3. Assess volume status: Check for dehydration, recent fluid losses, weight changes 1
4. Check for symptoms of hypoperfusion: dizziness, lightheadedness, confusion, chest pain, shortness of breath 1
5. Laboratory evaluation: Complete blood count (anemia), electrolytes (hyponatremia, hyperkalemia), glucose (diabetes), renal function, thyroid function 5, 6
6. Consider autonomic testing if neurogenic cause suspected, especially with diabetes or Parkinson's disease 6, 4

Important: Do not assume low BP is always benign—it requires evaluation to identify the underlying cause and prevent serious complications including falls, syncope, and organ hypoperfusion 2, 4