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.

Nearly half of all adults in many countries have hypertension. Many do not know it. Of those who are aware of it, only around half are receiving adequate treatment.

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

A hypertensive urgency describes readings above 180/120 mmHg without evidence of organ damage. A hypertensive emergency involves the same blood pressure threshold but with evidence of acute damage to the brain, heart or kidneys — a life-threatening condition requiring immediate hospitalisation.

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:

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 over 7 days provides a more accurate picture than isolated clinic readings and eliminates "white coat hypertension" (pressure elevated only in the medical setting) and "masked hypertension" (normal in clinic, elevated at home).

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

Treatment

Treatment aims to lower blood pressure to below 130/80 mmHg in most adults (or below 140/90 mmHg in older or frailer individuals), reducing long-term organ damage and cardiovascular events.

Lifestyle Modifications (First-Line for All Patients)

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 intravenous medications in an intensive care setting to lower blood pressure in a controlled, gradual manner — too rapid a drop can itself cause stroke or kidney damage.

Blood Pressure Assessment in China

China's tertiary hospitals offer comprehensive cardiovascular health assessments, including:

• Full hypertension work-up in a single visit: blood pressure classification, 24-hour ABPM, urine albumin-to-creatinine ratio, renal ultrasound, echocardiogram, and fasting metabolic panel
• Specialist investigation for secondary hypertension: aldosterone/renin ratio, renal artery Doppler, adrenal CT, sleep study
• Multidisciplinary cardiovascular risk management: combining cardiology, nephrology and endocrinology under one referral
• Transparent, published pricing — public hospital fees are set by regional health authorities

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 ChinaMedicalTour care navigator to arrange an assessment.

Medical content based on MSD Manuals, authored by Matthew R. Weir MD (University of Maryland School of Medicine), reviewed by Jonathan G. Howlett MD. Last reviewed February 2025.