The kidneys are situated in the posterior part of the abdomen, on either side of the vertebral column (spine) and surrounded by fat and loose areolar tissue.
Each kidney is about 11.25 cm in length, 5 to 7.5 cm in breadth, and more than 2.5 cm in thickness. The left kidney is somewhat longer and narrower than the right. The weight of the kidney in the adult male varies from 125 to 170 g and 115 to 155 g in the adult female. The combined weight of the two kidneys in proportion to that of the body is about 1:240.
Healthy kidneys clean your blood by removing excess fluid, minerals, and waste. They also make hormones that keep your bones strong and your blood healthy. When your kidneys fail, harmful wastes build up in your body, your blood pressure may rise, and your body may retain excess fluid and not make enough red blood cells. When this happens, you need treatment to compensate for your failed kidneys.