Causes of bloody urine include kidney infections, enlarged prostate, sickle cell anemia, kidney disease and bladder or kidney stones, states Mayo Clinic. Blood in the urine may come from the kidney, the bladder, the ureters or the urethra, according to WebMD.
Bacteria may move from the ureters or the bloodstream and enter the kidneys, leading to kidney infections, which may cause flank pain and fever, notes Mayo Clinic. The prostate gland may enlarge and press the urethra, partially blocking the urine flow and causing a persistent or an urgent need to urinate, difficulty urinating and blood in the urine. Defects of hemoglobin in red blood cells, an injury to the kidneys, and the formation of hard stones from crystals on the walls of the bladder or kidney may cause bloody urine.