Hypertension is a guaranteed exam topic because it combines a precise diagnostic process, a memorable stepwise treatment algorithm, and clear targets. This guide covers hypertension as examiners frame them, to the current NICE standard (NG136). Follow current guidance and local protocols in practice; this reflects guidance as of mid-2026.
What hypertension is
Hypertension is a persistently raised arterial blood pressure that increases the risk of stroke, ischaemic heart disease, heart failure, chronic kidney disease and dementia. The vast majority is primary (essential) hypertension with no single identifiable cause; a minority is secondary, from renal disease, endocrine causes such as primary hyperaldosteronism (Conn's), phaeochromocytoma or Cushing's, coarctation, or drugs. Consider a secondary cause in younger patients, those with resistant hypertension, or where there are suggestive features such as hypokalaemia (hyperaldosteronism), episodic symptoms (phaeochromocytoma) or radio-femoral delay (coarctation). Most hypertension, however, is asymptomatic and detected on routine measurement, which is why screening matters.
Diagnosis
A raised clinic reading is not enough to diagnose hypertension, because of the white-coat effect. Confirm with ambulatory blood pressure monitoring (ABPM) or, if not tolerated, home monitoring (HBPM). The thresholds reflect this:
- Stage 1: clinic blood pressure of 140/90 mmHg or higher, with an ABPM or HBPM daytime average of 135/85 or higher.
- Stage 2: clinic blood pressure of 160/100 or higher, with an ABPM or HBPM average of 150/95 or higher.
- Severe (stage 3): a clinic systolic of 180 or higher, or diastolic of 120 or higher.
ABPM and HBPM readings run about 5 mmHg lower than clinic readings. A severe reading prompts urgent assessment for target-organ damage; if there are signs such as retinal haemorrhage, papilloedema, new confusion, chest pain, heart failure or acute kidney injury, this is a hypertensive emergency needing same-day specialist care. At diagnosis, assess for target-organ damage and cardiovascular risk: check renal function and electrolytes, urine ACR for proteinuria, an ECG for left ventricular hypertrophy, fundoscopy, HbA1c and lipids, and calculate the QRISK score.
Who to treat
Offer drug treatment to everyone with stage 2 hypertension, and to people with stage 1 who also have target-organ damage, established cardiovascular disease, renal disease, diabetes, or a 10-year cardiovascular risk of 10% or more on QRISK. Lifestyle advice — salt reduction, weight, alcohol, exercise — is offered to all, and can meaningfully lower blood pressure alongside any drug treatment. Treatment decisions also weigh the person’s overall cardiovascular risk, not the blood pressure reading in isolation.
Treatment: the A/C/D algorithm
The stepwise pathway is heavily examined and turns on age and ethnicity:
- Step 1: for a person under 55 (and not of Black African or African-Caribbean family origin), or anyone with type 2 diabetes, start an ACE inhibitor or ARB (A). For a person aged 55 or over, or of Black African or African-Caribbean family origin without diabetes, start a calcium-channel blocker (C). If a CCB is not tolerated, use a thiazide-like diuretic such as indapamide (D).
- Step 2: combine — A plus C, or A plus D.
- Step 3: A plus C plus D, with doses optimised.
- Step 4 (resistant hypertension): confirm with ambulatory or home readings, check adherence, and add a fourth agent. If the potassium is 4.5 mmol/L or below, add low-dose spironolactone; if above 4.5, add an alpha- or beta-blocker. Seek specialist advice. Poor adherence is the commonest reason for apparent resistance, and should be checked before escalating.
A key nuance: an ARB is preferred over an ACE inhibitor when adding to a calcium-channel blocker in people of Black African or African-Caribbean family origin.
Targets
Treat to a clinic target below 140/90 for those under 80, and below 150/90 for those aged 80 and over, with corresponding ABPM or HBPM targets about 5 mmHg lower. Use clinical judgement in frailty or multimorbidity. Once blood pressure is controlled, monitor at least annually, reinforcing adherence and lifestyle and checking for drug side effects and end-organ damage.
High-yield exam points and traps
- Confirm hypertension with ABPM or HBPM — a single clinic reading is not enough.
- The A/C/D algorithm turns on age and ethnicity: ACE inhibitor or ARB for under-55s and diabetics; calcium-channel blocker for over-55s and those of Black African or African-Caribbean family origin.
- Type 2 diabetes means an ACE inhibitor or ARB at step 1, whatever the age or ethnicity, reflecting the renal protection these drugs offer in diabetes.
- The clinic target is below 140/90 under 80, and below 150/90 at 80 or over.
- Step 4 hinges on the potassium: spironolactone if 4.5 mmol/L or below, otherwise an alpha- or beta-blocker.
- A thiazide-like diuretic (indapamide) is preferred over a conventional thiazide.
- Always look for target-organ damage and secondary causes in the young or the resistant patient.
A few common questions
How is hypertension diagnosed? By a raised clinic reading confirmed with ambulatory or home monitoring, because of the white-coat effect; stage 1 is a clinic reading of 140/90 or higher with an ABPM or HBPM average of 135/85 or higher.
Which drug is first-line? First-line choice depends on the person: an ACE inhibitor or ARB for those under 55 or with type 2 diabetes, and a calcium-channel blocker for those 55 or over, or of Black African or African-Caribbean family origin.
What is the blood pressure target? Below 140/90 in clinic for people under 80, and below 150/90 for people aged 80 and over, with home and ambulatory targets about 5 mmHg lower.
What is resistant hypertension? Uncontrolled blood pressure despite an ACE inhibitor or ARB plus a calcium-channel blocker plus a thiazide-like diuretic at optimal doses; the fourth agent is guided by the potassium level.
When is hypertension an emergency? Hypertension is an emergency when a severe reading is accompanied by signs of target-organ damage — such as papilloedema, chest pain, heart failure or acute kidney injury — needing same-day specialist assessment; it can present with headache, visual disturbance or breathlessness.
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