What is the renal blood flow (RBF) of the kidney?

The kidneys receive approximately 20-25% of the cardiac output, which amounts to about 1-1.2 liters of blood per minute in a typical adult. This high blood flow is remarkable considering that kidneys make up less than 1% of total body weight. Blood enters the kidney through the renal artery, which branches into progressively smaller vessels until reaching the glomeruli, where filtration occurs. After filtration, blood flows through a series of capillaries surrounding the nephron tubules (peritubular capillaries and vasa recta) before exiting via the renal vein. This extensive blood supply serves the kidney's primary functions of filtering waste products, regulating electrolytes, maintaining acid-base balance, and controlling blood pressure. The kidney has autoregulatory mechanisms that maintain relatively constant blood flow despite fluctuations in systemic blood pressure, which is crucial for consistent filtration. Conditions like dehydration, heart failure, or certain medications can significantly alter renal blood flow, potentially affecting kidney function and overall health.