What is the most common cause of malignant hypertension (hypertensive emergency)?

The most common cause of malignant hypertension, also known as hypertensive emergency, is untreated hypertension. Malignant hypertension is characterized by extremely elevated blood pressure, often above 200/120 mmHg, and is associated with acute organ damage. Long-standing, poorly managed hypertension can lead to severe cardiovascular complications, which can escalate rapidly into a hypertensive crisis.

In patients with a history of untreated hypertension, the vascular system becomes increasingly strained, and the risk for acute complications such as stroke, renal failure, and heart attack significantly increases. This uncontrolled blood pressure can lead to a breakdown of regulatory mechanisms, resulting in further vasospasm and organ damage, which typifies malignant hypertension.

While other conditions such as pheochromocytoma and eclampsia can certainly lead to hypertensive episodes, they are less common causes compared to the complications arising from untreated hypertension. Operations can complicate untreated hypertension, but consistent management and control of blood pressure can greatly mitigate the risk of progressing to a malignant state. Thus, untreated hypertension stands out as the most prevalent and critical precursor to malignant hypertension.