What is the initial step in the workup and treatment of secondary hypertension?

Secondary Hypertension Workup

The initial step in the workup of secondary hypertension should be a thorough screening for specific clinical clues and risk factors, followed by targeted diagnostic testing based on the suspected underlying cause. 1, 2

When to Suspect Secondary Hypertension

Consider screening for secondary hypertension in patients with:

• Early onset hypertension (<30 years of age), especially without typical risk factors
• Resistant hypertension (BP >140/90 mmHg despite optimal doses of ≥3 antihypertensive medications including a diuretic)
• Sudden deterioration in previously well-controlled BP
• Hypertensive urgency or emergency
• Presence of strong clinical clues suggesting a secondary cause 1

Initial Evaluation

Before extensive workup, exclude pseudoresistance:

• Confirm proper BP measurement technique
• Rule out white coat effect with ambulatory BP monitoring
• Assess medication adherence
• Review current antihypertensive regimen for suboptimal choices 1

Diagnostic Approach by Suspected Cause

1. Renal Parenchymal Disease

• First-line test: Renal ultrasound and urinalysis
• Additional tests: Serum creatinine, eGFR, urine albumin-to-creatinine ratio 1, 2

2. Renovascular Hypertension

• First-line test: Renal Doppler ultrasound
• Additional tests: CT/MR angiography if ultrasound is positive or inconclusive 2

3. Primary Aldosteronism

• First-line test: Aldosterone-to-renin ratio
• When to suspect: Hypokalemia, resistant hypertension 2

4. Pheochromocytoma

• First-line test: 24-hour urinary or plasma metanephrines and normetanephrines
• When to suspect: Paroxysmal symptoms (headache, sweating, palpitations), labile BP 1, 2

5. Obstructive Sleep Apnea

• First-line test: Overnight polysomnography
• When to suspect: Snoring, daytime somnolence, obesity 2

6. Cushing's Syndrome

• First-line test: 24-hour urinary free cortisol or dexamethasone suppression test
• When to suspect: Central obesity, moon facies, striae, proximal muscle weakness 2

Common Pitfalls to Avoid

1. Failure to exclude pseudoresistance before extensive workup for secondary causes
2. Overlooking medication non-adherence as a cause of apparent treatment failure
3. Missing drug-induced hypertension from substances like NSAIDs, oral contraceptives, decongestants, or illicit drugs
4. Neglecting to assess for multiple secondary causes that may coexist
5. Delaying evaluation in patients with severe or rapidly progressive hypertension 1, 2

Management Principles

• Target the underlying cause with specific therapy when possible
• Maintain BP control with appropriate antihypertensive medications during diagnostic workup
• Consider referral to specialists for complex cases or when specialized testing is required
• Monitor for residual hypertension even after treating the secondary cause, as irreversible vascular remodeling may have occurred 1, 2

Key Considerations for Specific Populations

• Young patients (<30 years): Higher likelihood of secondary causes, particularly genetic/monogenic forms
• Elderly patients: Consider atherosclerotic renovascular disease and OSA
• Patients with resistant hypertension: Up to 50% may have an underlying secondary cause 2, 3

Remember that even after successful treatment of a secondary cause, blood pressure may not normalize completely due to concomitant essential hypertension or irreversible vascular changes, highlighting the importance of early detection and treatment.