What is the workup for secondary hypertension?

From the Guidelines

The workup for secondary hypertension should begin with a thorough history, physical examination, and basic laboratory tests, including serum sodium, potassium, eGFR, TSH, and dipstick urine analysis, as recommended by the 2020 international society of hypertension global hypertension practice guidelines 1. The initial evaluation should focus on identifying potential underlying causes of secondary hypertension, such as renovascular hypertension, primary aldosteronism, pheochromocytoma, Cushing's syndrome, and sleep apnea.

• Initial screening should include:
  • Complete blood count
  • Basic metabolic panel
  • Urinalysis
  • Thyroid function tests
  • Electrocardiogram
• Further investigations should be guided by the patient's history, physical examination, and basic laboratory results, and may include:
  • Renal ultrasound with Doppler or CT angiography for suspected renovascular hypertension
  • Measuring the aldosterone-to-renin ratio after discontinuing interfering medications for primary aldosteronism evaluation
  • Plasma free metanephrines or 24-hour urinary metanephrines and catecholamines for pheochromocytoma
  • Overnight dexamethasone suppression test or 24-hour urinary free cortisol for Cushing's syndrome screening
  • Polysomnography for sleep apnea evaluation
• Patients with resistant hypertension, sudden onset or worsening of hypertension, age under 30, no family history of hypertension, or presence of specific symptoms like headaches, palpitations, or excessive sweating should be suspected of having secondary hypertension, as stated in the 2024 esc guidelines for the management of elevated blood pressure and hypertension 1.
• Referral to a specialist center with expertise in hypertension management may be necessary for further evaluation and treatment, as recommended by the 2008 american heart association professional education committee of the council for high blood pressure research 1.

From the Research

Clinical Presentation of Secondary Hypertension

• Secondary hypertension can be suspected in subjects with onset of hypertension under 30 years of age, especially if in the absence of hypertensive family history or other risk factors for hypertension 2
• Treatment-resistant hypertension, severe hypertension (>180/110 mmHg), malignancy, or hypertensive emergencies can also raise suspicion of secondary hypertension 2, 3
• Clinical signs suspicious or suggestive of hypertension from endocrine causes, a "reverse dipping" or "non-dipping'" profile at 24 h ambulatory blood pressure monitoring not justified by other factors, signs of obvious organ damage may be helpful clues for diagnosis 2

Diagnostic Approach

• The assessment of patients begins with history taking and examination, to look for clinical clues 3
• Laboratory tests include electrolytes, urea, creatinine and the aldosterone:renin ratio, urinalysis and the urine albumin:creatinine ratio 3
• Abnormal results should prompt further investigation, and specialist advice can be sought if needed 3
• 24 h ambulatory blood pressure monitoring plays a central role in the work up of patients with suspected secondary hypertension 4

Common Causes of Secondary Hypertension

• Renal disease, primary aldosteronism, and obstructive sleep apnoea are common causes of secondary hypertension 3, 4
• Other causes include chronic kidney disease, pheochromocytoma, and drug-induced hypertension 5, 6
• Treatment is specific to the underlying cause and includes medications, procedures, surgery, and device therapies 6

Importance of Early Detection and Treatment

• Early detection and treatment of secondary hypertension are important to minimize/prevent irreversible changes in the vasculature and target organs 4
• Despite appropriate therapy or even removal of the secondary cause, BP rarely ever returns to normal with long-term follow-up, indicating either concomitant essential hypertension or irreversible vascular remodelling 4