What is the diagnostic and treatment approach for secondary hypertension?

Diagnostic and Treatment Approach for Secondary Hypertension

Screening for secondary hypertension is recommended when specific clinical indications and physical examination findings are present or in adults with resistant hypertension. 1

When to Suspect Secondary Hypertension

Secondary hypertension affects approximately 10% of hypertensive adults and should be suspected in patients with:

• Early-onset hypertension (<30 years of age)
• Resistant hypertension (BP >140/90 mmHg despite three optimal-dose medications including a diuretic)
• Sudden onset or worsening of previously controlled hypertension
• Severe hypertension or hypertensive emergency
• Target organ damage disproportionate to duration/severity of hypertension
• Onset of diastolic hypertension in older adults 1, 2

Diagnostic Algorithm

1. Initial Screening Tests (for all hypertensive patients):

   • Complete blood count
   • Basic metabolic panel (sodium, potassium, creatinine, eGFR)
   • Urinalysis and urinary albumin-to-creatinine ratio
   • Thyroid-stimulating hormone
   • 12-lead ECG 2

2. Targeted Evaluation based on clinical suspicion:

Renal Parenchymal Disease (1-2% prevalence)

• Clinical clues: History of urinary tract infections, hematuria, nocturia, elevated creatinine, abnormal urinalysis
• Physical findings: Abdominal mass (polycystic kidney disease), skin pallor
• Screening test: Renal ultrasound
• Confirmatory tests: Tests to evaluate cause of renal disease 1

Renovascular Disease (5-34% prevalence)

• Clinical clues: Resistant hypertension, abrupt onset/worsening hypertension, flash pulmonary edema, early-onset hypertension in women
• Physical findings: Abdominal systolic-diastolic bruit
• Screening test: Renal Duplex Doppler
• Confirmatory tests: Bilateral selective renal intra-arterial angiography, MRA, abdominal CT 1

Primary Aldosteronism (8-20% prevalence in resistant hypertension)

• Clinical clues: Resistant hypertension, hypokalemia, muscle cramps/weakness, family history of early-onset hypertension
• Physical findings: Arrhythmias (with hypokalemia)
• Screening test: Plasma aldosterone/renin ratio (standardized conditions)
• Confirmatory tests: Sodium loading test or IV saline infusion test, adrenal CT scan, adrenal vein sampling 1, 2

Obstructive Sleep Apnea (25-50% prevalence)

• Clinical clues: Resistant hypertension, snoring, fitful sleep, daytime sleepiness
• Physical findings: Obesity, Mallampati class III-IV, loss of normal nocturnal BP fall
• Screening test: Berlin Questionnaire, Epworth Sleepiness Score, overnight oximetry
• Confirmatory test: Polysomnography 1

Drug-Induced Hypertension (2-4% prevalence)

• Clinical clues: Temporal relationship between medication use and BP elevation
• Common culprits: NSAIDs, oral contraceptives, sympathomimetics, alcohol, illicit drugs, corticosteroids
• Management: Medication discontinuation or substitution when possible 1

Other Causes

• Pheochromocytoma: Screen with plasma free metanephrines or 24-hour urinary metanephrines
• Cushing's syndrome: Late-night salivary cortisol or overnight dexamethasone suppression test
• Coarctation of aorta: Echocardiography, CT angiography 2

Treatment Approach

1. Treat the underlying cause:

   • Renal parenchymal disease: Treat underlying kidney disease
   • Renovascular disease: Consider revascularization for fibromuscular dysplasia; medical therapy often preferred for atherosclerotic disease
   • Primary aldosteronism: Mineralocorticoid receptor antagonists or adrenalectomy for unilateral disease
   • Obstructive sleep apnea: CPAP therapy
   • Drug-induced: Discontinue or substitute offending agent 2

2. Optimize BP control while specific treatment is implemented:

   • Continue appropriate antihypertensive medications
   • Monitor BP response to specific interventions 1

3. Specialist referral: Referral to a physician with expertise in the specific form of secondary hypertension is reasonable for diagnostic confirmation and treatment 1

Important Considerations

• Despite appropriate therapy or removal of the secondary cause, BP may not return to normal due to concomitant essential hypertension or irreversible vascular remodeling 3
• Early detection and treatment are critical to minimize irreversible changes in the vasculature and target organs 2
• Comprehensive evaluation for secondary hypertension should be targeted and cost-effective, focusing on patients with clinical clues rather than screening all hypertensive patients 4