title: False 'hematuria' due to bacteriuria.
abstract: OBJECTIVE
  To determine the effects of bacteriuria on dipstick urinalysis for microhematuria.
  
  
  METHODS
  Selection of urine samples with dipstick readings of at least one plus (+) for blood, followed by microscopic examination and bacterial culture, from patients with signs and symptoms of urinary tract diseases.
  
  
  METHODS
  A large teaching hospital in Melbourne, Australia.
  
  
  METHODS
  Two hundred forty-six inpatients and outpatients being investigated for signs and symptoms of urinary tract diseases.
  
  
  RESULTS
  Seventeen (7%) of 246 patients having within-reference erythrocyte counts had polymicrobic cultures. One hundred nine patients had slight hematuria (1 x 10(7) to 6 x 10(7) cells/L). Of these, 21 bacteriuric patients had significantly higher dipstick findings than 88 abacteriuric patients (P < .005, Fisher's Exact Probability Test, two-tailed). Hydroperoxidase was detected in 80% of isolates (in 27 of 27 gram-negative bacilli cultures, in 6 of 6 staphylococci cultures, and in 3 of 12 streptococci cultures) on agar medium and in 69% of isolates in urine.
  
  
  CONCLUSIONS
  These results show that patients without hematuria but with bacteriuria may give a false-positive dipstick reading for blood.
authors.affiliation: Department of Microbiology, Royal Melbourne Hospital, Parkville, Victoria, Australia.
authors.forename: M H
authors.initials: MH
authors.lastname: Lam
mesh_terms: D001419:Bacteria / Q000378:metabolism; D001437:Bacteriuria / Q000150:complications*; D003937:Diagnosis, Differential; D004906:Erythrocyte Count; D005189:False Positive Reactions; D006417:Hematuria / Q000175:diagnosis / Q000209:etiology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D009195:Peroxidase / Q000378:metabolism; D016482:Urinalysis / Q000379:methods; D014556:Urine / Q000382:microbiology / Q000502:physiology; D014570:Urologic Diseases / Q000652:urine
chemical_list: D009195:Peroxidase