Hypertension (High Blood Pressure): Diagnosis and Management

Hypertension (high blood pressure) is one of the most common conditions in medicine and a major risk factor for stroke, heart attack, heart failure and chronic kidney disease. Because it usually causes no symptoms, it is often called a "silent" disease. Every doctor and medical student needs a clear approach to diagnosing and managing it.

Definition and diagnosis

Guidelines differ slightly. Under NICE (UK) guidance, hypertension is a clinic blood pressure of 140/90 mmHg or higher, confirmed by ambulatory or home monitoring averaging 135/85 mmHg or higher. American (ACC/AHA) guidelines use a lower threshold of 130/80 mmHg. Always confirm a raised reading on more than one occasion and, where possible, with out-of-office measurements to exclude "white-coat" hypertension.

Types and causes

• Primary (essential) hypertension — about 90% of cases; no single cause. Risk factors include age, family history, obesity, high salt intake, physical inactivity, excess alcohol and smoking.
• Secondary hypertension — has an identifiable cause. Think of it in young patients, sudden onset, resistant hypertension or suggestive features. Causes include kidney disease, renal artery stenosis, primary hyperaldosteronism, Cushing's syndrome, phaeochromocytoma, coarctation of the aorta, obstructive sleep apnoea and drugs (for example oral contraceptives, steroids and NSAIDs).

Assessment

Look for target organ damage and cardiovascular risk:

• Urine dipstick and albumin:creatinine ratio (kidney damage).
• Blood tests: kidney function, electrolytes, glucose or HbA1c, lipid profile.
• 12-lead ECG (left ventricular hypertrophy).
• Fundoscopy (hypertensive retinopathy).
• Calculate overall cardiovascular risk.

Management

Lifestyle — for everyone

• Reduce salt intake.
• Lose weight if overweight.
• Regular physical activity.
• Limit alcohol and stop smoking.
• A diet rich in fruit, vegetables and whole grains.

Medicines

The main drug classes are ACE inhibitors (for example ramipril), angiotensin receptor blockers (for example losartan), calcium channel blockers (for example amlodipine) and thiazide-like diuretics (for example indapamide). The choice depends on age, ethnicity, other conditions and local guidelines. For example, ACE inhibitors or ARBs are preferred in diabetes and chronic kidney disease with albuminuria. ACE inhibitors and ARBs should not be combined, and they must be avoided in pregnancy.

Many patients need two or more drugs. If blood pressure stays high despite three drugs at good doses, the patient has resistant hypertension: check adherence and measurement technique, and look for secondary causes.

Hypertensive emergency

Severely raised blood pressure (often 180/120 mmHg or higher) with acute organ damage — such as encephalopathy, stroke, acute coronary syndrome, acute heart failure, aortic dissection, acute kidney injury or eclampsia — is a hypertensive emergency. It needs hospital admission and controlled lowering of blood pressure, usually with intravenous drugs. Lowering the pressure too quickly can itself cause stroke or kidney injury.

Complications

• Stroke.
• Coronary artery disease and heart failure.
• Chronic kidney disease.
• Retinopathy.
• Aortic aneurysm and dissection.
• Peripheral arterial disease.

Exam pearls

• Always confirm the diagnosis with ambulatory or home readings where available.
• Hypokalaemia with hypertension suggests primary hyperaldosteronism.
• Radio-femoral delay in a young patient suggests coarctation of the aorta.
• Episodic headache, sweating and palpitations suggest phaeochromocytoma.
• ACE inhibitors cause a dry cough in some patients; ARBs are an alternative.

For a full chapter on hypertension and cardiovascular medicine, see our Medicine Companion.

Test yourself

5 exam-style single-best-answer questions. Choose your answer, then tap “Show answer”.

1. Under NICE guidance, which ambulatory average confirms hypertension?

   1. 130/85 mmHg or higher
   2. 150/95 mmHg or higher
   3. 120/80 mmHg or higher
   4. 135/85 mmHg or higher
   5. 160/100 mmHg or higher
   Show answer

   Answer: D. 135/85 mmHg or higher
   NICE: clinic BP 140/90 or higher confirmed by ambulatory or home average of 135/85 mmHg or higher.

2. A 32-year-old has hypertension and a low potassium. Which cause should be suspected?

   1. Primary hyperaldosteronism
   2. Hypothyroidism
   3. Anxiety
   4. White-coat hypertension
   5. Essential hypertension
   Show answer

   Answer: A. Primary hyperaldosteronism
   Hypertension with hypokalaemia suggests primary hyperaldosteronism (Conn's syndrome).

3. A hypertensive patient on an ACE inhibitor develops a persistent dry cough. What is the best alternative?

   1. Stop all treatment
   2. Add a second ACE inhibitor
   3. Switch to an angiotensin receptor blocker
   4. Give a cough syrup
   5. Add a beta-blocker only
   Show answer

   Answer: C. Switch to an angiotensin receptor blocker
   ACE-inhibitor cough is due to bradykinin; ARBs do not cause it and are the usual alternative.

4. Which drug class must be avoided in pregnancy?

   1. Nifedipine
   2. Labetalol
   3. Methyldopa
   4. Hydralazine
   5. ACE inhibitors and ARBs
   Show answer

   Answer: E. ACE inhibitors and ARBs
   ACE inhibitors and ARBs are teratogenic and must be avoided in pregnancy.

5. BP 210/130 mmHg with confusion and papilloedema. What is the correct approach?

   1. Give a diuretic only
   2. Recheck in one month
   3. Admit and lower blood pressure in a controlled way, usually with IV drugs
   4. Rapidly normalise blood pressure within minutes
   5. Send home with oral amlodipine
   Show answer

   Answer: C. Admit and lower blood pressure in a controlled way, usually with IV drugs
   This is a hypertensive emergency with organ damage. Controlled lowering prevents ischaemic injury from a too-rapid fall.

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Disclaimer

For education and exam preparation only. This is not medical advice and must not be used to diagnose or treat patients. Always follow current clinical guidelines and the advice of qualified senior colleagues.