What is the diagnostic and management approach for an 18-year-old with suspected secondary hypertension?

Diagnostic and Management Approach for an 18-Year-Old with Suspected Secondary Hypertension

In an 18-year-old with suspected secondary hypertension, you should immediately screen for renovascular disease (especially fibromuscular dysplasia), renal parenchymal disease, coarctation of the aorta, and primary aldosteronism, as these are the most common and treatable causes in this age group. 1

Initial Clinical Assessment

Key Historical and Physical Examination Findings to Identify

Obtain a focused history targeting:

• Exact age of hypertension onset (onset before age 30, especially before puberty, strongly suggests secondary causes) 1, 2
• Severity of blood pressure elevation and response to medications (resistant hypertension requiring ≥3 drugs suggests secondary causes) 1, 3
• Symptoms of episodic headaches, palpitations, sweating (pheochromocytoma) 4
• Muscle weakness or cramps (primary aldosteronism) 1
• Snoring, daytime sleepiness, witnessed apneas (obstructive sleep apnea) 4
• Urinary symptoms: frequency, nocturia, hematuria, history of urinary tract infections (renal parenchymal disease) 1, 4
• Medication use including over-the-counter drugs, herbal supplements, and illicit substances 1
• Family history of early-onset hypertension, stroke at young age, or polycystic kidney disease 1

Perform targeted physical examination for:

• Femoral pulse assessment and radio-femoral delay (coarctation of the aorta—particularly important in this age group) 1, 4, 3
• Abdominal bruits (renovascular hypertension) 1, 3
• Palpation for enlarged kidneys (polycystic kidney disease) 4, 5
• Cushingoid features: truncal obesity, purple striae, moon facies 3, 6
• Thyroid examination 4

Mandatory Initial Laboratory Screening

Order the following tests for all patients with suspected secondary hypertension: 1, 4, 5

• Serum creatinine and estimated glomerular filtration rate (eGFR)
• Serum sodium and potassium (spontaneous hypokalemia suggests primary aldosteronism)
• Urinalysis with dipstick for blood and protein
• Urinary albumin-to-creatinine ratio
• Fasting blood glucose or HbA1c
• Thyroid-stimulating hormone (TSH)
• Fasting lipid panel
• 12-lead electrocardiogram

Age-Specific Screening Priorities for 18-Year-Olds

Primary Aldosteronism Screening

Screen with plasma aldosterone-to-renin ratio in this patient, as the 2024 ESC guidelines now recommend considering this test in all adults with confirmed hypertension, and it has a prevalence of 8-20% in resistant hypertension. 1, 4 This represents a major departure from older guidelines that only recommended screening in specific high-risk scenarios. 1

If the aldosterone-to-renin ratio is positive, proceed with: 1, 4

• Confirmatory testing (intravenous saline suppression test or oral sodium loading test)
• Adrenal CT scan
• Referral to endocrinology or hypertension specialist for adrenal vein sampling if surgical intervention is being considered

Renovascular Disease Screening

In young patients, fibromuscular dysplasia is the most common cause of renovascular hypertension, not atherosclerotic disease. 1, 4, 2 Screen for renovascular disease if there is:

• Abrupt onset or sudden worsening of hypertension 1, 4
• Flash pulmonary edema 1, 2
• Abdominal bruits 1, 3
• Rise in serum creatinine ≥50% within one week of starting ACE inhibitor or ARB therapy 2

Initial imaging approach: 1, 4, 5

• Doppler renal ultrasonography (noninvasive first-line test in cooperative patients ≥8 years)
• CT angiography or MR angiography if ultrasound is suggestive or inadequate
• Avoid nuclear renography as it is less useful in pediatrics 1

Coarctation of the Aorta

This is a critical diagnosis not to miss in an 18-year-old. 1, 3 Assess for:

• Decreased or delayed femoral pulses compared to radial pulses 4, 3
• Blood pressure differential between upper and lower extremities
• Systolic murmur heard best over the back
• Rib notching on chest X-ray

If suspected, obtain echocardiography or CT/MR angiography of the aorta. 1, 4

Renal Parenchymal Disease

Screen with: 1, 4, 5

• Serum creatinine and eGFR (already part of initial workup)
• Urinalysis for blood, protein, and casts
• Renal ultrasound to assess kidney size, echogenicity, and presence of cysts or masses

Additional Targeted Investigations Based on Clinical Suspicion

If Pheochromocytoma is Suspected

• 24-hour urinary metanephrines or plasma free metanephrines 4, 5
• Abdominal/adrenal CT or MRI if biochemical testing is positive 4

If Obstructive Sleep Apnea is Suspected

• Home sleep apnea testing or polysomnography 4, 5
• This is less common in an 18-year-old unless there is obesity 1

If Cushing Syndrome is Suspected

• 24-hour urinary free cortisol or overnight dexamethasone suppression test 4, 6

Management Algorithm

If Secondary Cause is Identified

For fibromuscular dysplasia: Percutaneous transluminal renal angioplasty without stenting is the treatment of choice 4

For unilateral primary aldosteronism (adenoma): Surgical adrenalectomy is recommended 4, 7

For bilateral primary aldosteronism: Medical therapy with mineralocorticoid receptor antagonists (spironolactone 50-100 mg daily) 4, 7

For coarctation of the aorta: Surgical repair or endovascular stenting 1

For renal parenchymal disease: Treat the underlying kidney disease and use appropriate antihypertensive therapy 4

Antihypertensive Therapy During Workup

Target blood pressure in this 18-year-old should be <130/80 mmHg. 1 While investigating secondary causes:

• Initiate or optimize antihypertensive therapy to prevent target organ damage
• Avoid starting ACE inhibitors or ARBs until renovascular disease is ruled out, as these can precipitate acute kidney injury in bilateral renal artery stenosis 8, 2
• If primary aldosteronism is suspected, avoid or minimize diuretics during diagnostic testing as they can interfere with aldosterone-to-renin ratio interpretation 1

Referral Indications

Refer to a hypertension specialist, endocrinologist, or specialized center if: 1, 4, 9

• Screening tests are positive for secondary hypertension
• Hypertension is resistant to three-drug therapy including a diuretic
• Complex diagnostic testing or specialized procedures (adrenal vein sampling, renal angiography) are needed
• Surgical intervention is being considered

Critical Pitfalls to Avoid

Do not dismiss hypertension in an 18-year-old as "essential hypertension" without thorough evaluation. While primary hypertension can occur in young adults, especially in Black patients, the probability of secondary hypertension is substantially higher in this age group. 1, 3

Do not perform expensive imaging studies before completing basic laboratory screening. 4 The history, physical examination, and initial laboratory tests will guide which imaging studies are appropriate.

Do not delay diagnosis, as vascular remodeling from untreated secondary hypertension can result in residual hypertension even after the underlying cause is treated. 4, 5

Do not overlook medication-induced hypertension. 1, 4 Carefully review all prescription medications, over-the-counter drugs (especially NSAIDs, decongestants), herbal supplements, and illicit substances (cocaine, amphetamines) before pursuing extensive workup.

For pediatric and young adult patients, do not use electrocardiography to assess for left ventricular hypertrophy—echocardiography is the recommended modality. 1