From the Guidelines
The workup for secondary hypertension should begin with a thorough history, physical examination, and basic laboratory tests to identify potential underlying causes, as recommended by the 2020 international society of hypertension global hypertension practice guidelines 1. The initial screening should include a thorough assessment of history, physical examination, basic blood biochemistry (including serum sodium, potassium, eGFR, TSH), and dipstick urine analysis. Further investigations for secondary hypertension (additional biochemistry/imaging/others) should be carefully chosen based on information from history, physical examination, and basic clinical investigations 1. Some common causes of secondary hypertension and their corresponding diagnostic screening tests include:
- Renal parenchymal disease: renal ultrasound, tests to evaluate cause of renal disease
- Renovascular disease: renal Duplex Doppler, bilateral selective renal intra-arterial angiography, MRA, abdominal CT
- Primary aldosteronism: plasma aldosterone/renin ratio, oral sodium loading test, IV saline infusion test, adrenal CT scan, adrenal vein sampling
- Obstructive sleep apnea: Berlin Questionnaire, Epworth Sleepiness Score, overnight oximetry, polysomnography
- Drug or alcohol induced: urinary drug screen, response to withdrawal of suspected agent
- Pheochromocytoma/paraganglioma: 24-h urinary fractionated metanephrines, plasma metanephrines, CT or MRI scan of abdomen/pelvis
- Cushing’s syndrome: overnight 1-mg dexamethasone suppression test, 24-h urinary free cortisol excretion, midnight salivary cortisol Secondary hypertension should be suspected in patients with resistant hypertension (requiring ≥3 medications), sudden onset or worsening of hypertension, age <30 years without risk factors, or hypertension with specific clinical features like hypokalemia, abdominal bruits, or episodic symptoms 1. Identifying and treating the underlying cause can potentially cure the hypertension or significantly improve blood pressure control, with reduction in CVD risk 1. Consider referring for further investigation and management of suspected secondary hypertension to a specialist center with access to appropriate expertise and resources 1.
From the Research
Secondary Hypertension Workup
The workup for secondary hypertension involves identifying the underlying cause of the condition, which can be due to various factors such as renal disease, primary aldosteronism, obstructive sleep apnea, and others 2, 3, 4, 5, 6.
Clinical Clues and Screening
Clinical clues that should raise suspicion of secondary hypertension include early-onset, severe or resistant hypertension, suggestive family history, or specific clinical presentations 3, 6.
- Patients with clinical suspicion should be screened, as the workup can be time-consuming and expensive 2.
- 24-hour ambulatory blood pressure monitoring plays a central role in the workup of patients with suspected secondary hypertension 2.
- Laboratory tests, such as electrolytes, urea, creatinine, and the aldosterone:renin ratio, urinalysis, and the urine albumin:creatinine ratio, can help identify the underlying cause 3.
Common Causes and Associations
The most common causes and associations of secondary hypertension include:
- Renal disease 3, 5, 6
- Primary aldosteronism 3, 4, 6
- Obstructive sleep apnea 2, 3, 4, 6
- Medicines, illicit substances, and alcohol 3
- Pheochromocytoma and paraganglioma 4
- Cushing's syndrome 4
- Renovascular hypertension 4
- Coarctation of the aorta 6
- Chronic kidney disease 5
Diagnosis and Treatment
The diagnosis and treatment of secondary hypertension involve:
- History taking and examination to look for clinical clues 3
- Specialist advice if needed 3
- Treatment specific to the underlying cause, including medications, procedures, surgery, and device therapies 5
- Early detection and treatment to minimize or prevent irreversible changes in the vasculature and target organs 2, 4, 6