Hematuria may present microscopically or macroscopically, but the degree of hematuria is generally of little diagnostic or prognostic value. Drugs such as rifampin, sulfasalazine, and phenothiazines can also cause red discoloration of the urine.
Hematuria is a relatively common clinical finding.
Froom and colleagues reported a 40 percent incidence on routine urinalysis in 1,000 males between 18 and 33 years of age. Thirteen percent of postmenopausal women were reported to have hematuria on routine screening. Crystalluria caused by hypercalciuria or hyperuricosuria may often explain so-called idiopathic hematuria in asymptomatic persons. Crystal aggregates or microcalculi are thought to injure tubular epithelium, resulting in hematuria. Andres and colleagues found that more than 30 percent of children with isolated hematuria had hypercalciuria and a positive family history for nephrolithiasis.