Clinical reasoning notes. Targets and drug choices follow major guidelines; check your national protocol.
The reasoning chain: confirm the diagnosis properly → find out if there is a secondary cause → assess the organs already damaged and the other risks → treat with lifestyle and the right drug combination → set a target → follow up. Hypertension is silent: the aim of treatment is to prevent stroke, heart attack, heart failure and kidney disease.
1. Define and confirm
Hypertension is a sustained blood pressure of 140/90 mmHg or more in the clinic, confirmed on repeat visits (or ambulatory 24-hour monitoring at 130/80 or more, or home readings of 135/85 or more). Some guidelines use 130/80 as the threshold for treatment in high-risk patients.
Technique matters: rested seated patient, correct cuff size, arm at heart level, two or more readings. A cuff that is too small gives falsely high readings. White-coat hypertension is high in clinic and normal at home; masked hypertension is the reverse.
2. Stage and categorise
| Category | Blood pressure |
|---|---|
| Normal | below 120/80 |
| High-normal | 130–139 / 85–89 |
| Grade 1 | 140–159 / 90–99 |
| Grade 2 | 160–179 / 100–109 |
| Grade 3 | 180 or more / 110 or more |
| Hypertensive emergency | Very high BP with acute organ damage (encephalopathy, pulmonary oedema, aortic dissection, acute kidney injury, eclampsia) |
| Hypertensive urgency | Very high BP without acute organ damage |
3. Find the cause: primary or secondary?
About 90 to 95% is essential (primary). Suspect secondary hypertension when the patient is young (below 30), the BP is severe or resistant to three drugs, there is a sudden rise, or there are clues:
| Cause | Clues and test |
|---|---|
| Renal parenchymal disease | Abnormal creatinine, protein or blood in urine; kidney ultrasound |
| Renal artery stenosis | Abdominal bruit, flash pulmonary oedema, creatinine rise on ACE inhibitor; Doppler or CT angiography |
| Primary hyperaldosteronism (Conn) | Low potassium, high BP; aldosterone-to-renin ratio |
| Phaeochromocytoma | Episodes of sweating, headache, palpitations; urine or plasma metanephrines |
| Cushing syndrome | Moon face, striae; dexamethasone suppression test |
| Coarctation of the aorta | Young patient, radio-femoral delay, differing arm and leg BP |
| Thyroid disease, sleep apnoea, pre-eclampsia, drugs (NSAIDs, steroids, oral contraceptives, decongestants, herbal remedies, alcohol, liquorice) | History and tests |
4. Look for organ damage and other risks
| Test | The question it answers |
|---|---|
| Urea, creatinine, eGFR, urine albumin/creatinine ratio | Kidney damage as a cause or an effect? |
| Electrolytes | Low potassium suggests aldosteronism or diuretics |
| Glucose and HbA1c, lipid profile | Other cardiovascular risks |
| ECG | Left ventricular hypertrophy, strain, arrhythmia |
| Echocardiogram (if ECG or symptoms suggest) | Hypertrophy, heart failure |
| Fundoscopy | Hypertensive retinopathy (A-V nipping, haemorrhages, papilloedema in malignant hypertension) |
| Urinalysis | Protein and blood |
5. Management
Lifestyle (for everyone): reduce salt, lose weight, regular exercise, limit alcohol, stop smoking, a diet rich in fruit and vegetables.
Drugs: start with one of the four main classes, and combine early because most patients need two or more.
| Class | Example | Notes |
|---|---|---|
| ACE inhibitor / ARB | Enalapril, losartan | First line, especially with diabetes, heart failure or kidney disease. Contraindicated in pregnancy; check creatinine and potassium |
| Calcium channel blocker | Amlodipine | Often first line in people of African descent and older patients; ankle swelling |
| Thiazide-like diuretic | Indapamide, hydrochlorothiazide | Cheap and effective; watch potassium, sodium, gout |
| Beta-blocker | Bisoprolol | Not first line alone; used for angina, heart failure, arrhythmia; avoid in asthma |
Rule of thumb: a typical sequence is ACE inhibitor or ARB + calcium channel blocker, then add a thiazide-like diuretic, then spironolactone for resistant hypertension.
Target: most adults below 130/80 if tolerated (or at least below 140/90), checked on home or ambulatory readings. Treat statins and aspirin by overall cardiovascular risk, not blood pressure alone.
Hypertensive emergency: lower the pressure gradually (about 25% in the first hour) in a monitored setting with IV drugs. Dropping it too fast causes stroke. Aortic dissection and pre-eclampsia are exceptions with their own targets.
In pregnancy: use labetalol, nifedipine or methyldopa. Avoid ACE inhibitors, ARBs and thiazides.
6. Complications
Stroke, ischaemic heart disease, heart failure, chronic kidney disease, retinopathy, peripheral arterial disease, aortic dissection, and vascular dementia.
Examiner questions
- How do you confirm hypertension, and what is white-coat hypertension?
- When do you suspect a secondary cause, and which tests do you do?
- Which antihypertensives are contraindicated in pregnancy?
Practice questions
1. A 24-year-old woman has BP 190/110 and a low potassium. The most useful screening test is: A. Urine metanephrines · B. Aldosterone-to-renin ratio · C. Dexamethasone suppression · D. ASO titre · E. Chest X-ray Answer: B. Hypertension with hypokalaemia suggests primary hyperaldosteronism.
2. Which drug is contraindicated in a hypertensive pregnant woman? A. Labetalol · B. Nifedipine · C. Enalapril · D. Methyldopa · E. Hydralazine Answer: C.
3. A young patient has hypertension with weak femoral pulses and delayed radio-femoral pulses. The diagnosis is: A. Phaeochromocytoma · B. Cushing syndrome · C. Coarctation of the aorta · D. Renal artery stenosis · E. Conn syndrome Answer: C.
4. In a hypertensive emergency with encephalopathy, the blood pressure should be: A. Lowered to normal within minutes · B. Lowered gradually, about 25% in the first hour · C. Ignored · D. Treated with oral drugs only · E. Raised Answer: B.