Hypertension

3 min

Library·Cardiovascular·Hypertension

Don't miss

  • BP >180/110 with chest pain, vision change, severe headache, or breathlessness - same-day acute pathway
  • Pregnancy: BP >140/90 with proteinuria or symptoms - same-day O&G
  • Young or resistant: think 2° cause (renal artery, Conn's, OSA, phaeo)

First-line

BP target
<130/80 if 5-yr CVD risk ≥15%; otherwise <140/90
Drug ladder (NZ)
ACEi or ARB (under 55) → add CCB → add thiazide-like
Maori / Pacific / 55+
Start with CCB or thiazide-like
Lifestyle
Salt <2300 mg, alcohol, weight, sleep, movement

Refer when

  • Resistant: uncontrolled on 3 agents including a diuretic
  • Suspected secondary cause
  • Pregnancy-related; pre-conception planning on ACEi or ARB
  • End-organ damage on workup (renal, retinal, LVH)

Tell the patient

  • One high reading is not a diagnosis - ABPM or HBPM confirms
  • Lifestyle changes drop BP 5-10 mmHg - not optional, not the only lever
  • Side effects are usually manageable - ring before stopping

Confirming the diagnosis

A single elevated clinic reading is not hypertension. Confirm with either ambulatory blood pressure monitoring (ABPM, daytime average) or home blood pressure monitoring (HBPM, twice daily for 7 days, discard day 1, average the rest). White-coat hypertension is common and usually does not need treatment; masked hypertension is real and worth screening for in patients with known CVD risk and normal-looking clinic BPs.

Workup at diagnosis

  • Bloods: creatinine and eGFR, electrolytes, fasting glucose or HbA1c, lipid profile, TSH if clinically indicated
  • Urine: ACR (proteinuria), dipstick
  • ECG: baseline; consider echo if LVH on ECG, suspected heart failure, or murmur
  • CVD risk: calculate 5-year risk via PREDICT - the result drives the BP target

When to think secondary

Secondary hypertension accounts for around 5 to 10% of cases and is more likely in young patients, sudden-onset hypertension, resistant hypertension, or hypertension with hypokalaemia or other unexpected biochemistry. The screen depends on the suspicion:

  • Renal artery stenosis - asymmetric kidneys, deteriorating renal function on ACEi/ARB, audible bruit. Renal artery duplex.
  • Primary aldosteronism (Conn's) - hypertension with low or low-normal potassium, especially if resistant. Aldosterone-renin ratio off all interfering drugs.
  • Phaeochromocytoma - paroxysmal headaches, sweating, palpitations. Plasma metanephrines.
  • Obstructive sleep apnoea - common, under-diagnosed, contributes to resistance. Epworth, refer for sleep study.
  • Cushing's, hyperthyroidism, coarctation, drug-induced (NSAIDs, COC, decongestants, liquorice) - clinical clues drive workup.

Drug choice in detail

Start with the most appropriate single agent and uptitrate before adding a second. Do not combine ACEi with ARB. In NZ, candesartan and cilazapril are the most commonly used ARB and ACEi respectively (both well-funded), amlodipine is the default CCB, and indapamide or chlortalidone are preferred over older thiazides where available. Spironolactone (or eplerenone if intolerant) is the standard fourth-line agent for resistant hypertension.

Special populations

  • Diabetes: ACEi or ARB first regardless of age; tighter BP target in those with proteinuria
  • CKD: ACEi or ARB first; expect a small creatinine rise; reduce or stop if eGFR drops more than 25%
  • Pregnancy and pre-conception: labetalol, methyldopa, nifedipine MR; stop ACEi/ARB
  • Older adults: stand and check for postural drop; relax targets where falls risk is high

Monitoring after starting treatment

Recheck BP and renal function at 2 to 4 weeks after starting or up-titrating ACEi/ARB or diuretic. Once at target, 6 to 12 monthly review is typical, more often if comorbid. Encourage HBPM to keep the patient engaged and reduce reliance on clinic readings.