What is the initial workup for a patient with secondary hypertension?

Secondary Hypertension Workup

The initial workup for secondary hypertension should include a comprehensive metabolic panel, urinalysis, aldosterone-to-renin ratio, renal imaging, and specific targeted tests based on clinical suspicion according to the diagnostic table for suspected causes. 1

Clinical Presentation Suggesting Secondary Hypertension

Secondary hypertension should be suspected in the following scenarios:

• Severe or resistant hypertension
• Age of onset younger than 30 years (especially before puberty)
• Malignant or accelerated hypertension
• Acute rise in blood pressure from previously stable readings
• Hypertension with unexplained renal dysfunction
• Hypertension with specific symptoms suggesting underlying conditions 1, 2

Initial Diagnostic Workup

1. Confirm hypertension diagnosis:

   • Multiple blood pressure readings on different occasions
   • Consider ambulatory BP monitoring to rule out white-coat hypertension 1

2. Basic laboratory tests:

   • Complete metabolic panel (renal function, electrolytes, liver function)
   • Fasting blood glucose and HbA1c
   • Lipid profile
   • Urinalysis and urine albumin-to-creatinine ratio
   • TSH 1

3. Initial imaging:

   • Renal ultrasound (to assess kidney size, structure, and potential masses) 1

Targeted Testing Based on Suspected Cause

Suspected Cause	Clinical Clues	Recommended Screening Test
Primary aldosteronism	Hypokalemia, resistant hypertension	Aldosterone-to-renin ratio
Renovascular hypertension	Abdominal bruit, deteriorating renal function with ACEi/ARB	Renal Doppler ultrasound, CT/MR angiography
Pheochromocytoma	Episodic symptoms (headache, sweating, palpitations)	24h urinary/plasma metanephrines and normetanephrines
Obstructive sleep apnea	Snoring, daytime somnolence, obesity	Overnight polysomnography
Renal parenchymal disease	Abnormal urinalysis, elevated creatinine	Renal ultrasound, urinalysis, eGFR
Cushing's syndrome	Central obesity, striae, moon facies	24h urinary free cortisol, dexamethasone suppression
Thyroid disease	Tachycardia or bradycardia, weight changes	TSH
Hyperparathyroidism	Hypercalcemia, bone pain	PTH, calcium, phosphate
Coarctation of aorta	BP differential between arms and legs	Echocardiogram, CT angiogram [1]

Common Pitfalls and Caveats

• Don't miss medication-induced hypertension: Review all medications including OTC drugs, supplements, and recreational substances 3
• Avoid premature exclusion: Secondary hypertension affects approximately 5-10% of hypertensive adults but is more common in resistant hypertension (up to 20-30%) 1, 2
• Consider multiple causes: Some patients may have more than one contributing factor 1
• Beware of false positives: Certain medications can interfere with screening tests (e.g., antihypertensives affecting aldosterone-to-renin ratio) 1
• Don't overlook target organ damage: Assess for cardiac, renal, and neurological complications of hypertension 4

When to Refer

Consider specialist referral when:

• Diagnostic uncertainty persists
• Specialized testing is required
• Targeted treatment for specific secondary causes is needed
• Complex cases with multiple comorbidities 1

Management Approach

The management of secondary hypertension involves:

1. Treating the underlying cause when possible
2. Controlling blood pressure with appropriate medications
3. Monitoring for target organ damage
4. Regular follow-up to assess treatment efficacy 1, 3

For hypertensive emergencies (severe hypertension with end-organ damage), immediate admission to an intensive care unit with IV antihypertensive therapy is warranted 5.