What is Hypertension
Hypertension is a chronic condition defined as persistently elevated blood pressure ≥130/80 mm Hg (based on an average of ≥2 careful readings obtained on ≥2 occasions) or being on antihypertensive therapy. 1
Definition and Classification
Hypertension represents sustained elevation of arterial pressure that increases risk for cardiovascular disease, stroke, kidney disease, and death 1, 2. The 2025 AHA/ACC guidelines classify blood pressure into four categories based on systolic blood pressure (SBP) and diastolic blood pressure (DBP) 1:
- Normal BP: <120/<80 mm Hg
- Elevated BP: 120-129/<80 mm Hg
- Stage 1 Hypertension: 130-139/80-89 mm Hg
- Stage 2 Hypertension: ≥140/≥90 mm Hg
When SBP and DBP fall into different categories, the higher category determines classification 1. This classification system is designed for untreated adults and guides prevention and treatment decisions based on cardiovascular disease risk.
Epidemiology and Public Health Impact
Hypertension is the most prevalent modifiable cardiovascular risk factor and the leading cause of death and disability worldwide 1, 3. In the United States (2017-2020), the prevalence was 46.7% overall, with notable variations 1:
- By sex: Men 49.5% (59 million), Women 43.9% (56.3 million)
- By age: Increases dramatically from 20.3% (ages 18-29) to 83.7% (ages 75-80)
- By race/ethnicity: Highest in non-Hispanic Black adults (56.8%), followed by Hispanic (50.4%), non-Hispanic Asian (49.8%), and non-Hispanic White (47.0%)
Pathophysiology
The development of hypertension involves complex, interrelated mechanisms 2, 4:
- Renal dysfunction: Impaired pressure natriuresis (the kidney's ability to excrete sodium in response to elevated pressure) is present in all forms of chronic hypertension 4
- Neurohormonal activation: Excessive renin-angiotensin-aldosterone system and sympathetic nervous system activity 2, 4
- Vascular changes: Endothelial dysfunction, vascular remodeling, increased reactive oxygen species 3, 4
- Inflammatory processes: Elevated inflammatory cytokines and endothelin 4
In essential (primary) hypertension—which accounts for >90% of cases—the precise cause remains unknown, though excessive weight gain and dietary factors play major roles 4. This explains why hypertension is rare in non-obese hunter-gatherers in non-industrialized societies.
Clinical Significance
Hypertension is not merely an isolated elevation of blood pressure but represents metabolic impairment at the cellular level, genetically conditioned and triggered by various factors 5. Meta-analyses demonstrate that elevated BP and hypertension are associated with higher risk of cardiovascular disease, end-stage kidney disease, subclinical atherosclerosis, and all-cause mortality 1.
Common Pitfall
The lifetime risk of developing hypertension exceeds 90% in industrialized countries 6, yet fewer than half of those with hypertension are aware of their condition, and many aware patients remain untreated or inadequately treated 2. This represents a critical gap between disease prevalence and effective management.