The enzyme produced by the kidney that affects blood pressure is called

• A. Renin
• B. Renal sinus lipomatosis
• C. Pelviectasis
• D. Parapelvic cysts

Answer: (A)

Renin is the enzyme produced by the juxtaglomerular cells of the kidney. It kicks off the renin-angiotensin-aldosterone system (RAAS), which helps control blood pressure and fluid balance. When blood pressure is low, or sodium chloride delivery to the distal tubule decreases, the kidney releases renin. Renin converts angiotensinogen (from the liver) into angiotensin I, which is then turned into angiotensin II by ACE. Angiotensin II is a powerful vasoconstrictor and stimulates aldosterone release, leading to sodium and water retention—together these effects raise blood pressure. The other options describe structural renal conditions (fat in the renal sinus, dilation of the renal pelvis, or renal cysts near the pelvis) that do not involve an enzyme regulating blood pressure.