What is the initial work-up for a patient with secondary hypertension?

Initial Work-up for Secondary Hypertension

The initial work-up for a patient with suspected secondary hypertension should include routine laboratory tests (fasting blood glucose/HbA1c, serum lipids, sodium, potassium, creatinine/eGFR, TSH, urinalysis with albumin-to-creatinine ratio) and a 12-lead ECG to screen for common causes and assess cardiovascular risk. 1

Clinical Clues Suggesting Secondary Hypertension

• Early onset hypertension (<30 years of age), especially without typical risk factors like obesity or family history 2
• Resistant hypertension (BP >140/90 mmHg despite optimal doses of ≥3 antihypertensive drugs including a diuretic) 1
• Sudden deterioration in previously controlled blood pressure 1
• Hypertensive urgency or emergency 1
• Target organ damage disproportionate to duration or severity of hypertension 2

Comprehensive History and Physical Examination

History should focus on:

• Duration and previous levels of high blood pressure 1
• Symptoms suggesting secondary causes (headaches, palpitations, sweating episodes) 1
• Medication use that can raise blood pressure (NSAIDs, oral contraceptives, steroids, erythropoietin, cyclosporin) 1
• Lifestyle factors (salt intake, alcohol consumption, physical activity) 1
• Family history of hypertension, renal disease, or endocrine disorders 1

Physical examination should include:

• Features of Cushing syndrome (central obesity, moon face, buffalo hump) 1
• Skin stigmata of neurofibromatosis (suggesting pheochromocytoma) 1
• Palpation for enlarged kidneys (polycystic kidney disease) 1
• Auscultation for abdominal murmurs (renovascular hypertension) 1
• Auscultation for precordial or chest murmurs (aortic coarctation) 1
• Assessment of femoral pulses (diminished in aortic coarctation) 1

Routine Laboratory Tests

• Fasting blood glucose and HbA1c (if glucose is elevated) 1
• Serum lipids (total cholesterol, LDL, HDL, triglycerides) 1
• Blood sodium and potassium (hypokalemia suggests primary aldosteronism) 1
• Blood creatinine and eGFR (renal function assessment) 1
• Urinalysis and urinary albumin-to-creatinine ratio (renal damage) 1
• Thyroid-stimulating hormone (TSH) (thyroid dysfunction) 1
• 12-lead ECG (left ventricular hypertrophy, arrhythmias) 1

Further Investigations Based on Clinical Suspicion

For suspected primary aldosteronism:

• Plasma aldosterone-to-renin ratio (if hypokalemia or resistant hypertension) 2
• Confirmatory testing (intravenous saline suppression test) 1
• Adrenal imaging (CT scan) 1
• Adrenal vein sampling (to determine if unilateral or bilateral) 1

For suspected renovascular disease:

• Renal ultrasound with Doppler 1
• CT or MR renal angiography 1

For suspected pheochromocytoma:

• 24-hour urinary catecholamines or metanephrines 1
• Plasma free metanephrines 2
• Abdominal/adrenal imaging 1

For suspected obstructive sleep apnea:

• Home sleep apnea testing or polysomnography 1

Common Pitfalls to Avoid

• Failing to screen for secondary hypertension in high-risk patients (young patients, resistant hypertension) 2
• Not considering medication-induced hypertension before extensive workup 1
• Overlooking primary aldosteronism, which is more common than previously thought (8-20% of resistant hypertension) 2
• Performing expensive imaging studies before completing basic laboratory screening 1
• Not referring complex cases to specialized centers with appropriate expertise 1

Algorithm for Secondary Hypertension Work-up

1. Complete routine laboratory tests and ECG for all suspected cases 1
2. If clinical suspicion persists based on initial evaluation, proceed with targeted testing 1
3. Consider referral to specialist centers for complex cases or when initial testing suggests secondary causes 1
4. Remember that even after treating the underlying cause, some patients may require ongoing antihypertensive therapy due to vascular remodeling 3