What is the most common cause of secondary hypertension in children, characterized by a hum or bruit in the CVA?

The most common cause of secondary hypertension in children, particularly associated with the cardiovascular findings of a hum or bruit in the costovertebral angle (CVA), is renal artery stenosis. This condition can lead to hypertension due to the reduced blood flow to the kidneys, which stimulates the renin-angiotensin system, resulting in elevated blood pressure.

In children, renal artery stenosis can be due to various factors, including congenital malformations or fibromuscular dysplasia, which affects the structure of the blood vessels. While fibromuscular dysplasia can cause renal artery stenosis, it is more commonly seen in older patients. The presence of a bruit or hum in the CVA is indicative of turbulent blood flow, which occurs because of narrowing in the arteries, further supporting the diagnosis of renal artery stenosis as a significant cause of secondary hypertension in pediatric patients.

Thus, recognizing the acoustic signs and their correlation with underlying renal issues is crucial in diagnosing secondary hypertension effectively in children.