Polycystic Kidney Disease (PKD) is a condition where fluid-filled cysts grow in the kidneys. They form in the nephrons, or tiny tubes, within the kidney. The nephrons are tiny tubes that produce urine in the process of removing waste from the blood. There are about 1,000,000 nephrons in each human kidney. When the cysts grow in number and size, they can be painful and make the kidneys less able to or unable to function.
