Hypertension: Definition, Causes, and Common Symptoms
Hypertension is defined as persistent systolic blood pressure ≥130 mmHg or diastolic blood pressure ≥80 mmHg, affecting approximately one-third of the US adult population and over 1 billion adults worldwide. 1, 2
Definition and Classification
The American Heart Association and American College of Cardiology classify blood pressure into the following categories:
| Category | Systolic BP (mmHg) | Diastolic BP (mmHg) |
|---|---|---|
| Normal | <120 | and <80 |
| Elevated | 120-129 | and <80 |
| Stage 1 Hypertension | 130-139 | or 80-89 |
| Stage 2 Hypertension | ≥140 | or ≥90 |
For proper diagnosis, blood pressure should be measured at least twice during two or more separate visits over 1-several weeks, using a properly calibrated device and correct measurement technique 1. Home and ambulatory blood pressure monitoring are useful tools to confirm diagnosis and identify white-coat or masked hypertension 3.
Causes of Hypertension
Hypertension can be classified as primary (essential) or secondary:
Primary (Essential) Hypertension
- Accounts for approximately 90% of hypertension cases 4
- Results from complex interactions between:
- Genetic factors
- Environmental influences
- Pathophysiological mechanisms affecting multiple systems 5
Secondary Hypertension
- Accounts for approximately 10% of cases 4
- Caused by identifiable and potentially correctable conditions:
- Renovascular disease
- Renal parenchymal disease
- Primary hyperaldosteronism
- Drug and substance use (including NSAIDs, oral contraceptives, decongestants)
- Obstructive sleep apnea
- Less common: pheochromocytoma, Cushing syndrome, thyroid disorders, aortic coarctation 4
Risk Factors for Developing Hypertension
- Obesity/overweight
- Physical inactivity
- High sodium intake
- Low potassium intake
- Excessive alcohol consumption
- Family history
- Advancing age
- Diabetes mellitus
- Chronic kidney disease 1, 3
Common Symptoms
Hypertension is often called the "silent killer" because most patients with hypertension are asymptomatic. However, when symptoms do occur, they may include:
Symptoms of Uncomplicated Hypertension
- Most patients are asymptomatic
- Non-specific symptoms sometimes reported:
- Headaches (particularly occipital, occurring in the morning)
- Dizziness
- Blurred vision
- Fatigue
- Palpitations 5
Symptoms of Hypertensive Crisis
When blood pressure is severely elevated (systolic >180 mmHg or diastolic >120 mmHg), patients may develop a hypertensive crisis with symptoms related to end-organ damage:
Neurological symptoms:
- Severe headache
- Altered mental status
- Seizures
- Visual disturbances
Cardiovascular symptoms:
- Chest pain
- Shortness of breath
- Palpitations
Renal symptoms:
- Decreased urine output
- Edema 6
Complications of Untreated Hypertension
Uncontrolled hypertension significantly increases the risk of:
- Cardiovascular disease (coronary artery disease, heart failure)
- Stroke
- Chronic kidney disease
- Retinopathy
- Peripheral vascular disease 3, 1
The relationship between blood pressure and cardiovascular risk is continuous, with no evidence of a threshold, starting from blood pressure as low as 110 mmHg systolic 1. For every 10 mmHg reduction in systolic blood pressure, the risk of cardiovascular events decreases by approximately 20-30% 2.
Importance of Early Detection and Treatment
Despite the availability of effective treatments, only 44% of US adults with hypertension have their blood pressure controlled to less than 140/90 mmHg 2. Among those with uncontrolled hypertension:
- 33% are unaware of their condition
- 20% are aware but not being treated
- 47% are being treated but not adequately controlled 7
Early detection and proper management of hypertension are essential to reduce the risk of cardiovascular events and mortality. Treatment involves lifestyle modifications and, when necessary, pharmacological therapy with first-line medications including thiazide diuretics, ACE inhibitors, ARBs, and calcium channel blockers 1, 2.