Potential reasons for blood in urine include bladder or kidney infections, bladder stones, kidney stones and strenuous exercise, explains WebMD. It also occurs due to sickle cell anemia; an enlarged prostate; bladder, prostate or kidney tumors; and cystic kidney disease. Taking penicillin or aspirin can also cause blood in urine.
Runners are most likely to experience visible blood in the urine as a result of vigorous exercise, although almost any type of workout can cause it to happen, states Mayo Clinic. The bleeding may occur because the exercise caused trauma to the bladder, or it can be a sign of dehydration following the workout. Sometimes, exercise-related urinary bleeding occurs because performing aerobic exercise for a sustained period of time breaks down red blood cells.
Other medications that can cause blood in the urine include cyclophosphamide, heparin and phenazopyridine, notes WebMD. In addition, the bleeding may be a sign of a kidney injury if the patient has recently been in an accident or played sports. Yet another potential cause of blood in the urine is a condition called glomerulonephritis, which results when the filtering system for the kidneys becomes inflamed. Factors that can trigger glomerulonephritis include diabetes, diseases of the blood vessels, staph infections, viruses and IgA nephropathy, as Mayo Clinic explains.