What are the causes of acute hypertension?

Causes of Acute Hypertension

The majority of patients with acute hypertension have unrecognized or uncontrolled essential hypertension, but secondary causes are found in 20–40% of cases presenting with malignant hypertension, most commonly renal parenchymal disease and renal artery stenosis. 1

Primary Causes

Uncontrolled Essential Hypertension

• Medication non-adherence is the most common trigger for hypertensive emergencies, with many patients presenting without having received any antihypertensive medication. 1
• Limited access to healthcare frequently contributes to the development of hypertensive emergencies, particularly among sub-Saharan African migrants and African Americans. 1

Secondary Causes (20–40% of Cases)

Renal Causes

• Renal parenchymal disease is one of the most common secondary causes of malignant hypertension. 1
• Renal artery stenosis represents another frequent secondary etiology. 1
• Acute kidney injury can both cause and result from acute severe hypertension through disruption of renal autoregulation. 2

Endocrine Causes

• Pheochromocytoma can present as a hypertensive crisis with sudden severe hypertension accompanied by palpitations, diaphoresis, and headache. 2, 3
• Primary aldosteronism accounts for a notable proportion of secondary etiologies in malignant hypertension. 2
• Cushing syndrome can cause secondary hypertension. 4
• Thyroid disease (both hypothyroidism and hyperthyroidism) may contribute to hypertensive presentations. 4

Drug-Induced Hypertension

• Sympathomimetics (cocaine, methamphetamine) can cause acute severe hypertension with potential organ damage. 2
• NSAIDs contribute to acute blood pressure elevations. 2
• Steroids and immunosuppressants (including cyclosporine, tacrolimus) can precipitate hypertensive crises. 2
• Antiangiogenic therapy used in cancer treatment may cause acute hypertension. 2
• Interaction between tyramine-containing foods or drugs and monoamine oxidase inhibitors can trigger hypertensive emergencies. 3

Vascular Causes

• Acute aortic dissection presents with severe hypertension and requires immediate recognition. 1
• Coarctation of the aorta is a common cause in children and young adults. 4
• Atherosclerotic renal artery stenosis is particularly common in adults 65 years and older. 4

Pregnancy-Related

• Severe preeclampsia and eclampsia represent obstetric hypertensive emergencies. 1

Other Causes

• Obstructive sleep apnea contributes to secondary hypertension. 4
• Acute stress and sympathetic hyperreactivity (including PTSD, anxiety, pain) can cause transient severe blood pressure elevations. 2, 5
• Intracranial hemorrhage or acute stroke can both cause and result from acute hypertension. 1

Pathophysiological Mechanisms

Renin-Angiotensin System Activation

• Marked activation of the renin–angiotensin system is often present and associated with the degree of microvascular damage in malignant hypertension. 1
• Pressure-induced natriuresis contributes to blood volume contraction and further renin–angiotensin system activation. 1

Microvascular Damage

• Acute hypertensive microangiopathy is preceded by increased renal vasoconstriction and microvascular damage leading to endothelial dysfunction and thrombotic microangiopathy. 1

Clinical Context

Age-Related Patterns

• In children, renal parenchymal disease and coarctation of the aorta are the most common causes. 4
• In adults 65 years and older, atherosclerotic renal artery stenosis, renal failure, and hypothyroidism predominate. 4

Red Flags for Secondary Causes

• Age of onset younger than 30 years (especially before puberty) suggests secondary hypertension. 4
• Severe or resistant hypertension despite multiple medications warrants evaluation for secondary causes. 4
• Acute rise in blood pressure from previously stable readings should prompt investigation. 4
• Increase in serum creatinine ≥50% within one week of initiating ACE inhibitor or ARB therapy suggests renovascular hypertension. 4

After stabilization of any hypertensive emergency, screening for secondary causes is essential, as 20–40% of patients have identifiable and potentially reversible etiologies. 2