What causes hypertension?

Causes of High Blood Pressure (Hypertension)

High blood pressure is primarily caused by a complex interplay of genetic predisposition and environmental factors, with obesity, excess sodium intake, insufficient physical activity, and poor diet being the most significant modifiable risk factors. 1

Primary (Essential) Hypertension

Most patients (approximately 90%) have primary or essential hypertension, where the exact cause remains unknown, while about 10% have secondary hypertension with an identifiable cause 2. The pathophysiology involves complex interactions between:

Genetic Factors

• Hypertension is a complex polygenic disorder with more than 25 rare mutations and 120 single-nucleotide polymorphisms identified 1
• Currently, genetic variants account for only about 3.5% of blood pressure variability 1

Environmental and Lifestyle Factors

• Obesity: One of the strongest risk factors - being continuously obese or acquiring obesity is associated with a 2.7-fold increased risk of developing hypertension 1

  • May be responsible for 40-78% of hypertension cases according to attributable risk estimates
  • Central obesity (measured by waist-to-hip ratio) has an even stronger relationship with blood pressure than BMI

• Sodium intake: Excessive sodium consumption directly links to blood pressure increases 1

  • Salt sensitivity is more common in Black individuals, older adults, and those with comorbidities like chronic kidney disease, diabetes, or metabolic syndrome

• Physical inactivity: Sedentary lifestyle contributes significantly to hypertension risk 1

• Diet quality: Poor dietary patterns lacking fruits, vegetables, and whole grains 1

• Alcohol consumption: Excessive alcohol intake raises blood pressure 1

Pathophysiological Mechanisms

• Vascular changes: 2

  • Endothelial dysfunction
  • Altered vasoreactivity
  • Vascular remodeling
  • Fibrosis and inflammation
  • Increased peripheral vascular resistance

• Multiple organ system involvement: 2

  • Renal mechanisms
  • Cardiovascular adaptations
  • Central nervous system regulation
  • Hormonal networks

Secondary Hypertension

Secondary hypertension (approximately 10% of cases) results from identifiable underlying conditions 1. Key causes include:

1. Renal parenchymal disease: 2

   • Chronic glomerulonephritis
   • Polycystic kidney disease
   • Hypertensive nephrosclerosis

2. Renovascular disease: Renal artery stenosis should be suspected in: 2

   • Onset of hypertension before age 30 (without family history)
   • Significant hypertension after age 55
   • Presence of abdominal bruit with diastolic component
   • Accelerated or resistant hypertension
   • Recurrent flash pulmonary edema
   • Unexplained renal failure
   • Acute renal failure after ACEI/ARB therapy

3. Endocrine disorders: 2

   • Primary aldosteronism (suggested by unprovoked hypokalemia)
   • Pheochromocytoma (suggested by labile hypertension or paroxysms with headache, palpitations, pallor)
   • Cushing syndrome (suggested by truncal obesity, glucose intolerance, purple striae)
   • Hyperparathyroidism (suggested by hypercalcemia)

4. Other causes: 2, 1

   • Obstructive sleep apnea
   • Aortic coarctation (suggested by decreased pressure in lower extremities or delayed/absent femoral pulses)
   • Medication-induced hypertension

Risk Amplification

Hypertension risk is significantly amplified when multiple factors coexist: 1, 3

• Type 2 diabetes
• Obesity
• Dyslipidemia
• Sedentary lifestyle
• Smoking

Clinical Implications

If left untreated, hypertension leads to hypertension-mediated organ damage (HMOD) affecting: 2

• Heart (left ventricular hypertrophy, atrial fibrillation, heart failure)
• Brain (stroke, cognitive decline)
• Kidneys (acute and chronic kidney disease)
• Eyes (retinopathy)
• Blood vessels (macrocirculation and microcirculation damage)

These changes progress from asymptomatic to symptomatic, ultimately resulting in overt cardiovascular disease events unless properly treated 2.