Common causes of bleeding kidneys include kidney stones, injuries and kidney infections, according to Mayo Clinic. Some bleeding could indicate more serious problems such as advanced kidney disease, cancer or hereditary diseases.
Injuries, such as a blow from a sports injury, can cause bleeding. The injury results in visible blood in the urine, reports Mayo Clinic.
Kidney stones form from minerals in concentrated urine. They begin as crystals but eventually form hard stones. Most of the time, kidney stones are painless; however, Mayo Clinic indicates they become painful when they form a blockage or pass through the urinary tract. Kidney stones result in both microscopic and gross bleeding. Kidney infections, like urinary tract infections, cause microscopic bleeding in the kidneys. Kidney infections sometimes cause flank pain and fever.
Glomerulonephritis from kidney disease causes bleeding. In some cases, it forms on its on, but Mayo Clinic indicates it is sometimes a complication of diabetes or other systemic diseases. Infections can also cause glomerulonephritis.
Inherited conditions, including sickle cell anemia, are sometimes the cause of bleeding kidneys, indicates Mayo Clinic. Bleeding also occurs in the advanced stages of kidney cancer. Unfortunately, kidney cancer often does not present symptoms in the early stages when treatment is more effective.