Hypertension: Causes, Risk Factors, and Blood Pressure Management

The Silent Damage Inside Arteries

Roughly 119 million American adults — nearly half the adult population — have hypertension, according to the Centers for Disease Control and Prevention. Most of them don't feel it. High blood pressure causes no symptoms in the vast majority of people until it has already damaged the heart, kidneys, brain, or eyes. That silence is what makes hypertension one of the most dangerous chronic conditions: it progresses unchecked until a crisis — a heart attack, a stroke, kidney failure — reveals what years of elevated pressure have done.

The World Health Organization estimates that hypertension is responsible for approximately 10.8 million deaths per year globally, more than any other single risk factor. Managing blood pressure is arguably the most impactful single intervention available to preventive medicine.

How Blood Pressure Works

Blood pressure is the force exerted by circulating blood against the walls of arteries. It is expressed as two numbers:

• Systolic pressure (top number): pressure during a heartbeat, when the heart contracts and forces blood into the arteries
• Diastolic pressure (bottom number): pressure between heartbeats, when the heart rests and refills

Both are measured in millimeters of mercury (mmHg). The cardiovascular system maintains blood pressure through a complex interplay of cardiac output, peripheral vascular resistance, blood volume, and neurohormonal systems — including the renin-angiotensin-aldosterone system (RAAS) and the sympathetic nervous system.

Classification of Blood Pressure

The 2017 American College of Cardiology / American Heart Association guidelines redefined hypertension, lowering the diagnostic threshold from 140/90 mmHg to 130/80 mmHg. This reclassification added approximately 31 million Americans to the hypertensive category.

A hypertensive crisis requiring emergency evaluation occurs when blood pressure exceeds 180/120 mmHg, particularly if accompanied by chest pain, shortness of breath, neurological symptoms, or back pain suggesting aortic dissection.

Primary vs. Secondary Hypertension

Approximately 90 to 95 percent of hypertension cases are classified as primary (essential) hypertension — meaning no single identifiable cause exists. It results from a combination of genetic predisposition, lifestyle factors, and age-related changes in vascular function.

The remaining 5 to 10 percent is secondary hypertension, caused by an identifiable underlying condition:

• Primary aldosteronism (the most common secondary cause, accounting for up to 10% of all hypertension)
• Renal artery stenosis
• Chronic kidney disease
• Obstructive sleep apnea
• Pheochromocytoma (adrenal gland tumor secreting catecholamines)
• Thyroid disorders (both hypothyroidism and hyperthyroidism)
• Certain medications: NSAIDs, oral contraceptives, decongestants, stimulants

Secondary hypertension should be suspected in younger patients, patients with resistant hypertension (uncontrolled on three or more medications), or patients with clinical features suggesting a specific cause.

Risk Factors for Primary Hypertension

• Age: Prevalence rises sharply with age; by age 65, over 70% of adults are hypertensive
• Obesity: Every 5 kg/m² increase in BMI raises systolic blood pressure by approximately 3 mmHg
• Dietary sodium: High sodium intake increases blood volume and raises blood pressure, particularly in "salt-sensitive" individuals
• Physical inactivity: Regular aerobic exercise lowers resting blood pressure by 5–8 mmHg
• Alcohol consumption: More than 2 drinks per day is associated with increased blood pressure
• Family history: Genetic factors explain an estimated 30–60% of blood pressure variability
• Race: Hypertension is more prevalent and occurs at younger ages in Black Americans than in white Americans; outcomes are also more severe

Target Organ Damage

Sustained hypertension damages organs in characteristic ways:

• Heart: Left ventricular hypertrophy, coronary artery disease, heart failure
• Brain: Stroke (both ischemic and hemorrhagic), vascular dementia, cerebral small vessel disease
• Kidneys: Hypertensive nephrosclerosis, progressive chronic kidney disease
• Eyes: Hypertensive retinopathy, retinal artery occlusion, vision loss
• Peripheral arteries: Peripheral arterial disease, aortic aneurysm

Treatment: Lifestyle Modification

For Stage 1 hypertension without cardiovascular disease, lifestyle modification is often recommended before or alongside medication. Evidence-based interventions include:

Antihypertensive Medications

The four major first-line drug classes for hypertension are thiazide diuretics (e.g., chlorthalidone), ACE inhibitors (e.g., lisinopril), angiotensin II receptor blockers (ARBs, e.g., losartan), and calcium channel blockers (e.g., amlodipine). Choice depends on patient comorbidities:

• Diabetes or proteinuria: ACE inhibitors or ARBs preferred (protect the kidneys)
• Heart failure with reduced ejection fraction: ACE inhibitor or ARB, beta-blocker, and loop diuretic
• Prior myocardial infarction: Beta-blocker and ACE inhibitor or ARB
• Black patients without heart failure or diabetes: Thiazide diuretic or calcium channel blocker preferred (ACE inhibitors are less effective in this population)

Treatment targets for most patients are below 130/80 mmHg per the 2017 ACC/AHA guidelines. Resistant hypertension — defined as blood pressure above goal despite three antihypertensive agents of different classes, including a diuretic — affects approximately 10 percent of treated hypertensive patients and warrants additional evaluation and specialized management.

This article is for informational purposes only. Consult a qualified healthcare professional before making any health decisions.