Normal kidneys are about the size of a closed fist. Polycystic kidneys have cysts that form in the kidneys. These cysts are filled with fluid and, depending on their size and how many there are, will change the size of the kidneys. There are medical journals showing pictures of polycystic kidneys that are about the size of a football and weigh over 20 pounds. In addition to changing the size of the kidney, the cysts can interfere with healthy kidney functions and after time lead to kidney failure. About half of the people diagnosed with polycystic kidney disease will experience end stage renal disease (ESRD) and will need dialysis or a kidney transplant. PKD is most commonly believed to equally affect men and women of all races. However, some studies have shown that the disease may occur more often in white people than in African Americans and in females more often than males. PKD is the number four cause of kidney failure in Americans, and an estimated 600,000 people in the U.S. currently have it.