Polycystic kidney disease (PKD) is a genetic disorder characterized by the growth of numerous cysts filled with fluid in the kidneys. Cysts are sacs of fluid that cause the kidney to enlarge and can hinder its filtering ability. Cysts also squeeze on blood vessels forcing the pressure to rise. There may be just a few cysts or many, and the cysts may range in size from a pinhead to the size of a grapefruit. When many cysts develop, the kidneys can grow to be the size of a football. The first symptom is often high blood pressure. Other symptoms include fatigue, frequent urination, blood in urine, headaches, kidney stones or urinary tract infections. Complications of the disease can be loss of kidney function, brain aneurysms, mitral valve prolapse in the heart, frequent infections, chronic flank or back pain, pancreas or liver cysts, enlarged heart, kidney stones, groin or abdominal hernias and diverticulitis of the colon.