Who should be screened for a cause of secondary hypertension? How do I screen?

The clinical context and the outcome of investigations that should be carried out on all hypertensive patients will determine who should be investigated for secondary causes of hypertension.

Routine tests that should be performed

• Urinalysis. Proteinuria is suggestive of underlying renal damageor a causative lesion within the kidney.
• Routine biochemistry. This may suggest the presence of renaldysfunction (urea, creatinine, uric acid) or underlying endocrinedisease (Conn’s, Cushing’s, hyperparathyroidism).
• Electrocardiography. This may show the effects of long standingor poorly controlled hypertension (left ventricular hypertrophy,left axis deviation).

Further testing

If routine testing reveals abnormalities or the patient has been referred for “resistant hypertension” then further investigations are justified. These should be determined by clinical suspicion (for example, symptoms or signs of phaeochromocytoma, Cushingoid appearance etc.) and the outcome of routine investigations (for example proteinuria, haematuria, hypokalaemia etc.).

• Urinalysis. 24 hour quantification of protein, electrolytes, andcreatinine clearance.
• Radiological. Initially, ultrasound examination of the abdomenscreens renal size, anatomy and pelvicalyceal disease. Computerised tomography of the abdomen scan has greater sensitivity for adrenal tumours and phaeochromocytomas. MIBG scanning will help identify extra-adrenal phaeochromocytoma. Renal angiography will identify renal artery stenosis.
• Renal biopsy should be performed if microscopy or plasma immunological screening is suggestive of systemic inflammatory or renovascular disease.
• Endocrine investigations. 24 hour urinary cortisol (Cushing’s syndrome), 24 hour noradrenaline/adrenaline/dopamine (catecholamine-secreting tumours), and plasma renin and aldosterone (Conn’s syndrome) may all be warranted.