What is an early finding that may suggest renal artery stenosis in a 3 year old?

Increased blood pressure is an early finding that may suggest renal artery stenosis in a 3-year-old. This is primarily due to the kidneys' role in regulating blood pressure; when there is a narrowing of the renal artery, the kidneys may react by releasing renin, an enzyme that leads to an increase in angiotensin II. This hormone causes vasoconstriction, which subsequently elevates blood pressure. Children with renal artery stenosis often present with hypertension, which can be one of the first signs before more severe symptoms develop.

Other options, while they may indicate various medical conditions, are not specifically linked to renal artery stenosis in the same way. Decreased urine output can occur in many renal conditions but is less specific for stenosis. Swelling in the abdomen may suggest other issues, such as fluid retention or other abdominal pathologies. Pallor of the skin can indicate anemia or poor perfusion but isn't a direct sign of renal artery stenosis. Thus, increased blood pressure stands out as a critical and early indicator of renal artery stenosis in young children.