From the Guidelines
Secondary hypertension is most commonly caused by renal parenchymal disease, renovascular hypertension, primary aldosteronism, chronic sleep apnea, and substance/drug-induced hypertension, as identified in 5%–10% of hypertensive patients 1.
Common Causes of Secondary Hypertension
The most common causes of secondary hypertension include:
- Renal parenchymal disease, which impairs the kidneys' ability to regulate blood pressure, with a prevalence of 1%–2% 1
- Renovascular disease, which affects 5%–34% of patients with secondary hypertension, often presenting with resistant hypertension or hypertension of abrupt onset 1
- Primary aldosteronism, accounting for 8%–20% of cases, characterized by resistant hypertension, hypokalemia, and muscle cramps or weakness 1
- Obstructive sleep apnea, contributing to 25%–50% of cases, through intermittent hypoxia and sympathetic activation 1
- Drug or alcohol-induced hypertension, affecting 2%–4% of patients, caused by substances such as NSAIDs, oral contraceptives, and stimulants like cocaine and amphetamines 1
Diagnosis and Treatment
Diagnosing secondary hypertension involves a thorough medical history, physical examination, laboratory tests, and imaging studies to identify the underlying cause. Treatment focuses on addressing the primary condition while managing blood pressure with appropriate medications until the underlying cause is controlled. According to the 2020 International Society of Hypertension Global Hypertension Practice Guidelines, early diagnosis and targeted treatment of secondary hypertension can potentially cure hypertension in some patients or improve blood pressure control and reduce the number of prescribed antihypertensive medications in others 1.
Key Considerations
When evaluating patients with secondary hypertension, it is essential to consider the clinical indications, physical examination findings, and screening tests to guide the diagnosis and treatment plan. For example, patients with primary aldosteronism may present with arrhythmias, especially atrial fibrillation, and require a plasma aldosterone/renin ratio under standardized conditions to confirm the diagnosis 1. Similarly, patients with obstructive sleep apnea may exhibit obesity, Mallampati class III–IV, and loss of normal nocturnal blood pressure fall, and require polysomnography to confirm the diagnosis 1.
From the Research
Secondary Causes of Hypertension
The secondary causes of hypertension refer to high blood pressure caused by an identifiable and potentially correctable condition or disease. Some of the common causes of secondary hypertension include:
- Renovascular disease
- Renal parenchymal disease
- Primary hyperaldosteronism
- Drug and substance use
- Obstructive sleep apnea Less common etiologies include:
- Pheochromocytoma/paraganglioma
- Cushing syndrome
- Thyroid and parathyroid conditions
- Congenital adrenal hyperplasia
- Aortic coarctation 2, 3, 4
Prevalence of Secondary Hypertension
An identifiable secondary cause of hypertension is present in approximately 10% of adult patients with hypertension 2. The prevalence and potential etiologies of secondary hypertension vary by age, with renal parenchymal disease and coarctation of the aorta being common causes in children, and atherosclerotic renal artery stenosis, renal failure, and hypothyroidism being common causes in adults 65 years and older 4.
Diagnosis and Management
Early recognition of suggestive clinical findings and laboratory results enables the timely diagnosis of specific secondary causes of hypertension 2. The selection of patients for testing should incorporate historical and clinical clues, previous treatment course, and comorbidities 3. Management involves treating the underlying condition, and some patients may benefit from referral to a specialist with specific expertise in treating the causative condition 2, 3. Targeted therapies can supplement first-line antihypertensive agents, and optimal approaches to diagnosis and management of common causes of secondary hypertension include primary aldosteronism, renovascular hypertension, obstructive sleep apnea, and drug-induced hypertension 5.