Hypertension (High Blood Pressure): The Silent Killer

Hypertension (High Blood Pressure): The Silent Killer

High blood pressure — or hypertension — is a condition in which the force of blood pushing against the artery walls remains persistently elevated. It is called the "silent killer" because it rarely causes noticeable symptoms while quietly damaging the heart, blood vessels, kidneys and brain over years.

WHO estimates that 1.4 billion adults aged 30–79 had hypertension worldwide in 2024, about 33% of that age group. Many remain undiagnosed or inadequately controlled. This WHO estimate uses its population definition of hypertension; prevalence changes with the age group and diagnostic threshold used.

Understanding Blood Pressure Readings

A blood pressure reading records two numbers:

• Systolic pressure — the peak pressure as the heart contracts and pushes blood into the arteries
• Diastolic pressure — the resting pressure between beats, as the heart refills

Blood pressure is expressed as systolic / diastolic in millimetres of mercury (mmHg), for example 120/80 mmHg — read as "120 over 80."

Blood Pressure Classification in Adults

The table follows the 2025 US AHA/ACC framework for adults. Other guidelines use different diagnostic thresholds; use the framework agreed with your clinician. When the two numbers fall into different categories, the higher category applies.

Category	Systolic (mmHg)	Relationship	Diastolic (mmHg)
Normal	Below 120	AND	Below 80
Elevated	120–129	AND	Below 80
Stage 1 Hypertension	130–139	OR	80–89
Stage 2 Hypertension	140 or higher	OR	90 or higher
Severe hypertension requiring prompt assessment	Above 180	OR	Above 120

In a nonpregnant adult, a systolic reading above 180 or a diastolic reading above 120 needs prompt attention. If there are no concerning symptoms, repeat the measurement after at least one minute and contact a healthcare professional promptly if it remains very high. Severe pressure with acute organ injury is a hypertensive emergency. Chest pain, severe breathlessness, new weakness, difficulty speaking, confusion or new visual changes require immediate emergency help; do not wait for both numbers to cross a threshold or for a repeat reading when such symptoms are present. Pregnancy has separate assessment thresholds.

Causes and Risk Factors

Primary (Essential) Hypertension

Around 90–95% of hypertension cases have no single identifiable cause. This is called primary or essential hypertension. It develops gradually over many years and reflects the cumulative effect of multiple influences:

• Genetics — a family history of hypertension significantly raises personal risk
• Age — arteries stiffen naturally with age; blood pressure rises progressively after age 30–40
• Obesity — doubles the risk; excess weight increases blood volume and arterial resistance
• Physical inactivity — reduces cardiovascular fitness and promotes weight gain
• High sodium (salt) intake — causes fluid retention and raises blood pressure in susceptible individuals
• Excess alcohol consumption — a consistent independent risk factor
• Smoking — acutely raises blood pressure and promotes arterial damage
• Chronic stress — activates the sympathetic nervous system, raising pressure temporarily; chronic stress may contribute to sustained elevation
• Diabetes — promotes arterial stiffness and kidney-related blood pressure dysregulation

Secondary Hypertension

In 5–10% of cases, hypertension has an identifiable underlying cause:

• Chronic kidney disease — impairs fluid and salt regulation
• Primary aldosteronism — overproduction of a sodium-retaining hormone by the adrenal glands
• Renal artery stenosis — narrowing of the arteries supplying the kidneys
• Obstructive sleep apnoea — recurrent overnight oxygen drops stimulate pressure-raising hormones
• Thyroid and adrenal disorders — hypothyroidism, hyperthyroidism, Cushing's syndrome, phaeochromocytoma
• Certain medications — NSAIDs, combined oral contraceptives, decongestants, stimulants

Secondary hypertension is important to identify because it may be curable by treating the underlying condition.

Why High Blood Pressure Is Dangerous

Hypertension forces the heart to pump against higher resistance continuously. Over years, this causes:

Organ	Consequence
Heart	Left ventricular hypertrophy → heart failure; coronary artery disease; heart attack
Brain	Stroke (both ischaemic and haemorrhagic); vascular dementia
Kidneys	Hypertensive nephropathy → chronic kidney disease → dialysis
Eyes	Hypertensive retinopathy → vision impairment
Arteries	Accelerated atherosclerosis; aortic aneurysm

The relationship between blood pressure and cardiovascular risk is continuous — there is no safe threshold. Even within the "elevated" range (120–129 mmHg systolic), risk is already higher than in those with optimal pressure.

Symptoms

Hypertension rarely causes symptoms until it is severe or complications have occurred. Occasional headache, nosebleeds or dizziness are often attributed to high blood pressure, but they are neither sensitive nor specific — most people with these symptoms have normal blood pressure, and most with hypertension have none of them.

Symptoms that should prompt urgent assessment include:

• Severe headache, particularly at the back of the head on waking
• Visual disturbances
• Chest pain or breathlessness
• Confusion or neurological changes

These may signal a hypertensive emergency.

Diagnosis

Blood pressure measurement must be taken correctly to be meaningful:

• Patient seated quietly for 5 minutes before measurement
• Two or more readings on each of two or more separate occasions
• The average of these readings is used to classify blood pressure

Home blood pressure monitoring, following an agreed protocol over several days (often 7), helps compare usual pressure with clinic readings. It can help identify "white coat hypertension" (higher in clinic) and "masked hypertension" (higher outside the clinic); measuring pressure does not itself eliminate either pattern.

24-hour ambulatory blood pressure monitoring (ABPM) captures patterns across the full day, including night-time dipping, which carries independent prognostic significance.

Treatment

The 2025 US AHA/ACC guideline gives an overarching treatment goal below 130/80 mmHg, with additional considerations for people in institutional care, those with limited life expectancy and pregnancy. Agree your target with the treating clinician, taking account of the applicable guideline, frailty, symptoms on standing and treatment tolerance; older age alone is not a universal reason to use a 140/90 target.

Lifestyle Modifications (First-Line for All Patients)

Intervention	Expected BP Reduction
Weight loss (10 kg)	5–20 mmHg systolic
DASH diet (high fruit, vegetables, low saturated fat)	8–14 mmHg
Sodium restriction (<2,000 mg/day)	2–8 mmHg
Regular aerobic exercise (30 min, 5×/week)	4–9 mmHg
Limiting alcohol	2–4 mmHg
Stopping smoking	Does not lower resting BP but dramatically reduces overall cardiovascular risk

Antihypertensive Medications

First-line agents include:

• ACE inhibitors (e.g. ramipril, lisinopril) — particularly beneficial in diabetic patients and those with kidney involvement
• Angiotensin receptor blockers (ARBs) (e.g. losartan, valsartan) — used when ACE inhibitors cause cough
• Calcium channel blockers (e.g. amlodipine) — effective in older adults and those of African descent
• Thiazide diuretics (e.g. indapamide, hydrochlorothiazide) — low-cost and well-tolerated

Most patients with stage 2 hypertension require two or more drugs. Combination tablets improve adherence.

Treating Hypertensive Emergencies

A hypertensive emergency requires immediate hospital treatment, usually with intravenous medications and close monitoring in an intensive care setting. The blood-pressure target and speed of reduction depend on the specific acute organ injury; conditions such as acute aortic dissection require rapid, carefully controlled treatment. Excessive or uncontrolled lowering can itself cause harm.

Blood Pressure Assessment in China

For a planned blood-pressure assessment in China, confirm the receiving institution’s services and which investigations are clinically indicated:

• Initial assessment and planned tests: blood-pressure classification and selected urine, blood or imaging tests. A 24-hour ABPM recording takes place over a day and night, with device return and results review arranged separately; a complete work-up is not promised in one visit
• Secondary-hypertension investigation: the specialist decides whether tests such as an aldosterone/renin ratio, renal artery imaging, adrenal imaging or a sleep study are indicated; these are not routine for every person
• Specialist coordination: confirm whether cardiology, nephrology or endocrinology input is needed and how referrals will be arranged
• Costs and service scope — request an itemised hospital quote and confirm any separate coordination or translation charges before booking

If you have been told your blood pressure is elevated, have a strong family history, or wish to understand your full cardiovascular risk, contact a PriumCare care navigator to arrange an assessment.

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Sources and editorial correction

Background source: MSD Manual Professional: Hypertension, by Matthew R. Weir, MD, peer reviewed by Jonathan G. Howlett, MD. The source page lists a full review in February 2025 and an update in February 2026. Those credits and dates belong to the MSD source, not to authorship or clinical review of this PriumCare article.

• WHO: hypertension prevalence.
• AHA: 2025 blood-pressure guideline.
• AHA: severe readings and emergency symptoms.
• NICE NG136: diagnosis and home monitoring.
• NHS: 24-hour blood-pressure monitoring.

Editorial source correction: 25 October 2026. This targeted check addressed prevalence, threshold interpretation, monitoring, treatment-target context, service assertions and source attribution. It is not a clinical review of the whole article. No named medical reviewer of this PriumCare article is claimed. Original publication date is retained.

Targeted hypertensive-emergency clarification

Editorial source check: 26 October 2026. This update clarifies only that emergency blood-pressure targets and the rate of reduction depend on the acute organ injury, including acute aortic dissection. It is not a whole-article medical review, adds no named clinical reviewer, and retains the original publication date.

• ACC/AHA: acute aortic syndrome management recommendations
• AHA: elevated blood pressure in the acute care setting