What are the causes of hypotension (low blood pressure)?

From the Guidelines

Hypotension, or low blood pressure, is most commonly caused by dehydration, medications such as antihypertensives and diuretics, and heart problems, as well as endocrine disorders, severe infections, blood loss, and neurological conditions, with the most recent and highest quality evidence supporting these causes 1.

Causes of Hypotension

The causes of hypotension can be categorized into several groups, including:

• Dehydration from inadequate fluid intake, excessive sweating, vomiting, or diarrhea
• Medications, particularly antihypertensives (like beta-blockers, ACE inhibitors, diuretics), antidepressants, and drugs for Parkinson's disease
• Heart problems, such as heart failure, heart attack, or valve disorders, which can reduce the heart's pumping ability, leading to hypotension
• Endocrine disorders, including adrenal insufficiency, hypothyroidism, and diabetes, which can disrupt blood pressure regulation
• Severe infections causing sepsis, which can trigger dangerously low blood pressure
• Blood loss from trauma or internal bleeding, which reduces blood volume and pressure
• Neurological conditions affecting autonomic nervous system function, such as autonomic neuropathy, which can impair blood pressure control
• Anaphylaxis, a severe allergic reaction, which causes sudden hypotension
• Nutritional deficiencies, particularly B12 and folate, which may contribute to low blood pressure
• Pregnancy, which naturally lowers blood pressure, especially during the first 24 weeks
• Age-related changes to blood vessels and baroreceptor sensitivity, which can cause postural (orthostatic) hypotension in elderly individuals

Key Findings

A study published in 2005 found that beta-blockers, especially those that also block alpha-1-receptors, can produce hypotension, which is usually asymptomatic but may produce dizziness, lightheadedness, or blurred vision 1. Another study published in 2001 found that ACE inhibitors may induce hypotension in patients with high-grade bilateral renal artery stenosis or stenosis of a dominant or a single kidney, as well as in patients with atherosclerotic disease in smaller preglomerular vessels or afferent arteriolar narrowing due to hypertension or chronic cyclosporine use 1.

Recommendations

Based on the most recent and highest quality evidence, it is recommended to identify and address the underlying cause of hypotension, whether it be dehydration, medication-related, or due to an underlying medical condition, in order to prevent morbidity, mortality, and improve quality of life 1.

From the FDA Drug Label

The patient should be used with caution in orthostatic hypotensive patients who are also diabetic, as well as those with a history of visual problems who are also taking fludrocortisone acetate, which is known to cause an increase in intraocular pressure and glaucoma.

The causes of hypotension (low blood pressure) are not directly stated in the provided drug labels. However, it can be inferred that orthostatic hypotension can occur in various patients, including those with diabetes or a history of visual problems.

• Orthostatic hypotension is mentioned as a condition that midodrine is used to treat.
• The exact causes of hypotension are not explicitly stated in the labels 2 2.

From the Research

Causes of Hypotension

• Hypotension can be caused by various factors, including endocrine disorders, such as adrenal failure, isolated hypoaldosteronism, pseudohypoaldosteronism, pheochromocytoma, and neuro-endocrine tumors 3
• It can also be caused by non-endocrine factors, such as heart failure with reduced ejection fraction (HFrEF) 4
• Additionally, certain medications can induce orthostatic hypotension, particularly in older patients, including diuretics, calcium channel blockers, beta-blockers, angiotensin converting enzyme (ACE) inhibitors, nitrates, anti-Parkinsonian drugs, antidepressants, and antipsychotics 5, 6
• Autonomic dysfunction also plays a significant role in the development of orthostatic hypotension, especially in elderly individuals 5, 6
• Other causes of hypotension include neurogenic orthostatic hypotension, which is a disabling disorder caused by impairment of the normal autonomic compensatory mechanisms that maintain upright blood pressure 7

Specific Causes

• Adrenal failure can cause hypotension, either from primary adrenal origin or central origin 3
• Isolated hypoaldosteronism can also cause hypotension, and is generally classified according to its primary or secondary adrenal origin 3
• Pheochromocytomas can cause hypotension, especially during surgical removal when the patient has not been prepared with calcium inhibitors 3
• Carcinoid syndrome can cause hypotension, and is very sensitive to subcutaneous somatostatin analog 3
• Heart failure with reduced ejection fraction (HFrEF) can cause hypotension, particularly in patients with signs of shock and/or severe congestion 4