10 hypertension facts

10 hypertension facts

In this article we provide 10 medical revision notes on hypertension (high blood pressure).

Key Points

• Normal blood pressure – there is no such thing. But for most adults there is a normal range of between 100/70 and 135/85 mmHg.

  “130/80 is a good average target for most patients, and 120/70 if you have diabetes.”

  For most people, hypertension (or high blood pressure, BP) is ‘silent’, i.e. you cannot ‘feel’ whether it is high or low (asymptomatic). And for most people, high BP is ‘essential (or primary) hypertension’, i.e. there is no underlying cause.

• Hypertension is a common, and significantly increases the risk of cardiovascular disease, stroke, and kidney disease
• Diagnosis requires persistently elevated blood pressure (BP) readings, typically ≥140/90 mmHg.
• Management includes lifestyle modification and pharmacological treatment based on individual risk factors and blood pressure levels.
• Early detection and treatment can reduce the risk of long-term complications.

1. Definition

Hypertension, or high blood pressure, is defined as persistently elevated arterial blood pressure. The following thresholds are used for diagnosis:

• Clinic BP: ≥140/90 mmHg
• Ambulatory blood pressure monitoring (ABPM) or home blood pressure monitoring (HBPM): ≥135/85 mmHg. This is especially useful in suspected white coat hypertension. Hypertension can be classified as:
• Stage 1 Hypertension: Clinic BP ≥140/90 mmHg and ABPM/HBPM ≥135/85 mmHg
• Stage 2 Hypertension: Clinic BP ≥160/100 mmHg and ABPM/HBPM ≥150/95 mmHg
• Severe Hypertension: Clinic systolic BP ≥180 mmHg and/or diastolic BP ≥120 mmHg.

2. Epidemiology

• Hypertension affects about one-third of adults in the UK, with the prevalence increasing significantly with age
• It is more common in men than women until around 65 years, after which the prevalence becomes similar
• Hypertension is a leading modifiable risk factor for cardiovascular disease, stroke, chronic kidney disease (CKD), and heart failure.
• Many individuals remain undiagnosed due to the asymptomatic nature of the condition.

3. Risk factors

• Non-modifiable
  • Age: Risk increases with age, particularly over 60 years
  • Ethnicity: Higher prevalence in individuals of Afro-Caribbean and South Asian descent
  • Family history: Genetic predisposition contributes to higher risk.
• Modifiable
  • Obesity/sedentary lifestyle
  • Excessive salt intake
  • Excessive alcohol consumption
  • Smoking
  • Co-existing conditions: Diabetes, dyslipidaemia, and chronic kidney disease (CKD).

4. Causes

• Primary (essential) hypertension: Accounts for about 90-95% of cases, with no identifiable cause. It is likely multifactorial, involving genetics, lifestyle, and environmental factors.
• Secondary hypertension: Caused by an underlying condition, which may include:
  • Renal disease: Chronic kidney disease (all causes, especially renal artery stenosis (RAS); also known as renovascular disease, RVD)
  • Endocrine disease: Hyperaldosteronism (Conn’s Syndrome), phaeochromocytoma, Cushing’s Syndrome, hyperthyroidism
  • Medication: NSAIDs, corticosteroids, oral contraceptives, sympathomimetics
  • Obstructive sleep apnoea
  • Coarctation of the aorta
  • Aortic regurgitation (AR: with a wide pulse pressure)
  • Other: pregnancy (pre-eclampsia and eclampsia).

Note. BP is normally low in pregnancy. So 130/80 can be a disease.

5. Symptoms

• Usually asymptomatic: Hypertension is frequently referred to as a ‘silent killer’ because patients may not exhibit symptoms until complications arise.
• Non-specific symptoms (unusual)
  • Headaches: Usually occipital and worse in the morning.
  • Dizziness
  • Visual disturbances
  • Nosebleeds
  • Palpitations
  • Of an underlying cause.

6. Diagnosis

• Blood pressure measurement: Diagnosis requires multiple elevated readings on different occasions. Measure BP in both arms, taking the highest reading
• Ambulatory Blood Pressure Monitoring (ABPM): Considered the gold standard. It involves 24-hour monitoring to confirm persistent hypertension
• Home Blood Pressure Monitoring (HBPM): Useful for patients unable to undergo ABPM or those with ‘white coat hypertension’.

Investigation

• Routine blood tests: To assess for target organ damage and possible secondary causes:
  • Urea and electrolytes (U&Es): To check renal function
  • Fasting glucose or HbA1c: To screen for diabetes
  • Lipid profile: To assess cardiovascular risk
  • Thyroid function tests: If thyroid dysfunction is suspected
  • Endocrine tests (if indicated): e.g. for phaeochromocytoma.
• Urinalysis: To detect proteinuria or haematuria, which may indicate kidney disease
• ECG: To identify left ventricular hypertrophy (LVH), arrhythmias, or evidence of IHD
• Chest x-ray: heart size and structural disease (e.g. coarctation or AR)
• Echocardiogram: Consider if there is evidence of heart failure or a cardiac cause is suspected
• Renal ultrasound: To look for causes of CKD (e.g. PCKD); if renal artery stenosis is suspected, a CT renal angiogram is needed as well (and possibly a renal angiogram).

Differential diagnosis

• White coat hypertension: Elevated BP in a clinical setting but normal readings at home or on ABPM
• Secondary hypertension: Consider in cases of resistant hypertension, rapid onset in younger patients, or symptoms suggesting an underlying condition
• Pseudohypertension: In older adults, due to stiff, calcified arteries.

7. Treatment

1. Lifestyle modifications: First-line for all patients:
   • Reduce salt intake: Aim for less than 6 g/day
   • Adopt a balanced diet: Rich in fruits, vegetables, whole grains, and low in saturated fats
   • Regular physical activity: At least 150 minutes of moderate exercise per week
   • Limit alcohol consumption: No more than 14 units per week
   • Smoking cessation
   • Weight reduction: Aim for a BMI of under 30 (ideally 20-25) kg/m².
2. Treat secondary cause: e.g. referral to endocrine surgeon; or deliver the baby (preclampsia)
3. Pharmacological therapy:
   • Stage 1 Hypertension: Consider treatment if there is a 10-year cardiovascular risk of ≥10% (using the QRISK3 score), diabetes, or evidence of end-organ damage
   • Stage 2 Hypertension: Pharmacological treatment is recommended for all patients
     • First-line medication
       • ACE inhibitors (e.g. ramipril) or ARBs (e.g. losartan): Preferred in patients under 55 years or those with diabetes
       • Calcium channel blockers (e.g. amlodipine): Preferred in patients over 55 years or those of Afro-Caribbean descent (often require three drugs or more to control their BP)
       • Thiazide-like diuretics (e.g. indapamide): Consider if calcium channel blockers are not suitable.
     • Beta-blockers (e.g, Bisoprolol): Not first-line but may be used in specific cases (e.g. patients with heart failure, angina, or tachyarrhythmias). Labetolol is often used in pregnancy
     • Other vasodilators: e.g. Hydralazine. Minoxidil can be used by specialists for severe BP
     • Centrally acting drugs: e.g. Methyldopa (also used in pregnancy)
     • Combination therapy: Often required for effective control, involving drugs from different classes
4. Monitoring: Regular follow-up to monitor BP control (and U&Es), treatment adherence, and any potential side effects.

Note 1. If BP cannot be controlled on 3 drugs – patients should be referred to see a hospital consultant. These can be in various departments including cardiology, endocrinology or nephrology (depending on local practice).

Note 2. Role of loop diuretics and/or fluid restriction. This is especially useful in patients with CHF, CKD or nephrotic syndrome. In patients with advanced CKD (CKD4/5), uncontrolled hypertension can be one of the indications to start dialysis.

8. Complications

• Cardiovascular 
  • Ischaemic heart disease (IHD): Including myocardial infarction
  • Heart failure (acute and chronic): Due to long-standing pressure overload
  • Left ventricular hypertrophy (LVH)
  • Aortic dissection.
• Cerebrovascular 
  • Stroke: Both ischaemic and haemorrhagic
  • Transient ischaemic attacks (TIA).
• Renal
  • Acute kidney injury (AKI): Rare but can occur with any cause of accelerated hypertension
  • Chronic kidney disease (CKD): Due to hypertensive nephropathy (due to accelerated hypertension; also called a hypertensive emergency)
• Ophthalmic 
  • Hypertensive retinopathy: Can lead to visual impairment
• Cerebral
  • Hypertensive encephalopathy: Epilepsy, confusion, drowsiness or coma.

Note. Mild-moderate essential hypertension does not cause CKD. Other causes of CKD should be sought.

9. Prognosis

• Prognosis depends on timely diagnosis and effective management
• Untreated hypertension significantly increases the risk of cardiovascular events, CKD, and mortality
• With effective BP control and risk factor modification, the risk of complications can be substantially reduced, improving life expectancy and quality of life.

10. Prevention

• Primary prevention
  • Public health measures: Educating the public on the importance of a healthy lifestyle, diet, and regular exercise
  • Routine screening: Regular BP checks, particularly for individuals over 40 years old or those with risk factors
  • Patient education: Encouraging lifestyle changes in high-risk individuals, even before diagnosis.
• Secondary prevention
  • Ongoing management: Adherence to prescribed antihypertensive therapy and regular monitoring
  • Management of comorbidities: Optimising control of conditions such as diabetes, hyperlipidaemia, and CKD.

Patients should be encouraged to monitor their own blood pressure

And write it down! They can buy a BP machine from many chemists or large supermarkets or Amazon – prices vary, approximately £20-£40. ‘A&D’ is a good make.

This is some advice to give them regarding the method:

1. Frequency – measure it once a week until it reaches the target given to you, then once a month, then once every three months. Unless asked by your doctor, do not take it too frequently
2. Relax – go someone where you are relaxed, with no one talking to you
3. Arm – same arm
4. Time – same time of day – first thing in the morning is good
5. Three times – measure it three times, and take the lowest (usually the last one). Write it down, with previous ones. Show them to your doctor when you see them next.

Note. Even a relatively small decrease in blood pressure can have significant health benefits.

Summary

We have provided 10 medical revision notes on hypertension (high blood pressure). We hope it has been helpful.

Top Tip

Do not treat a single blood pressure measurement. Look at the pattern of BP in the patient after a full clinical assessment.

Other resources

What is normal BP?

MyHSN hypertension podcast (2024) – 7 min, 58 sec