Secondary Hypertension

On diagnosis, investigate all patients with hypertension for common comorbidities, complications, and secondary causes. Further investigations may be considered if treatment resistance or high risk of secondary HTN.

Initial investigations: urine dipstick for blood (phase contrast microscopy if positive), urine ACR, UEC, lipids, fasting glucose, Hb, ECG (LVH, AF, IHD).

Secondary hypertension

If hypertension is not controlled despite 3 drugs at maximal tolerated doses (including a diuretic), investigate for secondary hypertension. Also investigate for secondary hypertension in those who are young , always investigate children with hypertension.

Suggestive signs:

• Palpitations (phaeochromocytoma).
• Haematuria (renal disease).
• Delayed Femoral Pulse, Epigastric Bruit (Coarctation of the Aorta, Renal Artery Stenosis).
• Abnormal UECs — low K, elevated creatinine (Conn’s syndrome).

Investigation should be completed by specialists; initial tests include renal function, urine analysis for blood/protein (phase contrast microscopy if positive), and renal artery USS. Plasma Aldosterone/Renin Ratio for Hyperaldosteronism (Conn Syndrome) and Plasma Free Metanephrines or 24hr Urinary Fractionated Metanephrines if symptoms of episodic catecholamine excess -> palpitations, hot flushes.

Watch for the new national hypertension guideline due Q3 2026, which may revise this workup.