Cardiovascular · Hard
This case is fictional and exists for study. It describes no real patient.
54 years · male
A 54-year-old male of Black African origin presents for routine follow-up regarding his hypertension. He reports strict adherence to his maximum tolerated anti-hypertensive regimen, which comprises ramipril 10 mg once daily, amlodipine 10 mg once daily, and indapamide 2.5 mg once daily. He has no chest pain, shortness of breath, headache, or visual disturbances. His home blood pressure readings over the past two weeks average 154/96 mmHg. Physical examination shows heart sounds with no added sounds or murmurs, clear lung fields, and no peripheral oedema. Fundoscopy shows bilateral arteriolar narrowing and AV nipping without exudates or papilledema.
Vital signs
- HR
- 72 bpm
- BP
- 156/98 mmHg
- RR
- 16/min
- Temp
- 36.8 °C
- SpO₂
- 98%
Examination findings
- Grade 2 hypertensive retinopathy (arteriolar narrowing, AV nipping)
- Normal S1 and S2, no heart murmurs
- No peripheral oedema
Investigations
| Serum Sodium | 140 mmol/L | reference: 135-145 |
| Serum Potassium | 3.8 mmol/L | reference: 3.5-5.0 |
| Serum Creatinine | 90 µmol/L | reference: 60-110 |
| eGFR | 82 mL/min/1.73m² | reference: >90 |
| Urine Albumin-to-Creatinine Ratio | 1.8 mg/mmol | reference: <3.0 |
Question 1 of 3
According to NICE guidelines, what is the most appropriate pharmacological management step to add to this patient's current regimen?
This patient has resistant hypertension, defined as BP remaining elevated despite triple therapy with an ACEi/ARB, CCB, and thiazide-like diuretic at optimal doses. According to NICE guidelines (NG136), Step 4 treatment involves checking serum potassium. If serum potassium is ≤ 4.5 mmol/L, low-dose spironolactone (25 mg daily) is the recommended fourth-line agent. If serum potassium is > 4.5 mmol/L, an alpha-blocker (e.g., doxazosin) or beta-blocker (e.g., bisoprolol) should be selected instead. Ramipril 10 mg once daily is already the maximum recommended anti-hypertensive dose.
Teaching point: In resistant hypertension with serum potassium ≤ 4.5 mmol/L, Step 4 management requires adding low-dose spironolactone.
Question 2 of 3
Which of the following initial screening investigations is most appropriate to evaluate for the most common secondary cause of resistant hypertension in this patient?
Primary aldosteronism (Conn's syndrome) is the most common secondary cause of resistant hypertension, accounting for up to 20% of cases. Screening is recommended in resistant hypertension regardless of serum potassium levels (as hypokalaemia is absent in up to 60% of primary aldosteronism cases). The recommended initial screening test is the plasma aldosterone-to-renin ratio (ARR). Renal artery Doppler evaluates for renovascular disease, which is less prevalent. 24-hour urinary free cortisol tests for Cushing's syndrome, and 24-hour urinary metanephrines screen for pheochromocytoma, both of which are far rarer secondary causes.
Teaching point: Plasma aldosterone-to-renin ratio is the primary screening test for hyperaldosteronism, the most frequent secondary cause of resistant hypertension.
Question 3 of 3
Four weeks after initiating spironolactone 25 mg once daily, his blood pressure improves to 134/84 mmHg. Blood tests show serum potassium 4.9 mmol/L (3.5-5.0) and creatinine 102 umol/L (baseline 90 umol/L). What is the single most appropriate management action?
The patient's blood pressure is now well-controlled on Step 4 therapy. His serum potassium (4.9 mmol/L) remains within the normal range (≤ 5.0 mmol/L), and the mild rise in serum creatinine (< 30% increase from baseline) is expected after adding a mineralocorticoid receptor antagonist to an ACE inhibitor. Therefore, all current medications should be continued, and potassium and renal function should be routinely monitored in 1-2 months. Discontinuing or reducing doses of either medication is unnecessary and would lead to loss of blood pressure control.
Teaching point: When initiating spironolactone alongside ACE inhibitor therapy, mild non-progressive increases in creatinine and potassium ≤ 5.0 mmol/L are acceptable and warrant continuation with monitoring.
Key learning points
- Resistant hypertension is defined as blood pressure above target despite treatment with maximum tolerated doses of three anti-hypertensives (A + C + D).
- Step 4 NICE anti-hypertensive guidance specifies adding low-dose spironolactone if potassium is ≤ 4.5 mmol/L, or an alpha/beta-blocker if potassium is > 4.5 mmol/L.
- Primary aldosteronism is the most common secondary cause of resistant hypertension and is screened using the plasma aldosterone-to-renin ratio.
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