What are the causes of hypertension?

Causes of Hypertension

Hypertension is primarily caused by a complex interaction between genetic predisposition and environmental/lifestyle factors, with approximately 90% of cases being primary (essential) hypertension and about 10% having an identifiable secondary cause. 1

Primary (Essential) Hypertension

Genetic Factors

• Polygenic disorder with multiple genes influencing blood pressure
• More than 25 rare mutations and 120 single-nucleotide polymorphisms identified
• Genetic variants collectively account for only about 3.5% of blood pressure variability
• Presence of multiple small-effect alleles leads to more rapid BP increases with age 1
• Rare monogenic forms exist (e.g., glucocorticoid-remediable aldosteronism, Liddle's syndrome, Gordon's syndrome) 1

Environmental and Lifestyle Factors

Obesity and Overweight

• Strong, direct relationship between body mass index and blood pressure
• Central obesity (measured by waist-to-hip ratio) shows even stronger correlation
• May be responsible for 40-78% of hypertension cases
• Continuous weight gain increases risk; becoming normal weight reduces risk to baseline 1

Dietary Factors

• Sodium intake: Positively associated with BP; accounts for much age-related BP increase
• Insufficient potassium intake: Associated with higher BP
• Other dietary deficiencies: Calcium, magnesium, protein (especially from vegetables), fiber, and fish fats 1
• Poor overall diet quality: Contributes significantly to hypertension risk 1

Physical Activity

• Sedentary lifestyle increases hypertension risk
• Regular physical activity helps maintain healthy blood pressure 1

Alcohol Consumption

• Dose-dependent relationship with blood pressure
• Particularly problematic at ≥3 drinks/day 1

Psychosocial Factors

• Chronic stress and job strain (especially in men)
• Social factors like urbanization and education level 2

Secondary Hypertension

Secondary hypertension accounts for approximately 10% of cases and has identifiable causes:

Renal Causes

• Chronic kidney disease
• Renovascular disease (renal artery stenosis)
• Post-renal urinary tract obstruction 1

Endocrine Causes

• Primary aldosteronism
• Pheochromocytoma
• Cushing's syndrome
• Thyroid disorders (hyperthyroidism)
• Hyperparathyroidism
• Acromegaly 1

Sleep Apnea

• Obstructive sleep apnea strongly associated with resistant hypertension
• Characterized by snoring, hypersomnolence, and observed apneas 1

Medication and Substance-Induced

• NSAIDs
• Oral contraceptives
• Sympathomimetics
• Alcohol
• Illicit drugs (cocaine, amphetamines)
• Anticancer drugs (especially vascular endothelial growth factor inhibitors)
• Corticosteroids
• Licorice (excessive consumption) 1

Vascular Causes

• Coarctation of the aorta
• Arterial stiffening with age 1

Clinical Evaluation for Causes

Key Historical Features

• Primary hypertension: Gradual BP increase, lifestyle risk factors, family history
• Secondary hypertension: BP lability, specific symptoms (e.g., palpitations, snoring), medication use, absence of family history 1

Physical Examination

• Vital signs including proper BP measurement
• BMI/waist circumference
• Signs of target organ damage
• Signs suggesting secondary causes (e.g., abdominal bruits, cushingoid features) 1

Basic Laboratory Testing

• Fasting blood glucose
• Complete blood count
• Lipid profile
• Serum creatinine with eGFR
• Electrolytes (sodium, potassium, calcium)
• Thyroid-stimulating hormone
• Urinalysis
• Electrocardiogram 1

Additional Testing for Suspected Secondary Causes

• Imaging: Echocardiography, renal ultrasound, CT/MRI
• Functional tests: Aldosterone-renin ratio, plasma metanephrines, sleep studies 1

Pathophysiological Mechanisms

Hypertension results from dysregulation of multiple systems:

• Increased peripheral vascular resistance
• Endothelial dysfunction
• Vascular remodeling
• Fibrosis and inflammation
• Sympathetic nervous system overactivity
• Renin-angiotensin-aldosterone system dysfunction
• Renal sodium handling abnormalities 1

If untreated, these mechanisms lead to hypertension-mediated organ damage affecting the heart, brain, kidneys, eyes, and blood vessels, ultimately resulting in cardiovascular disease events 1.