Comparison of urinary lactic dehydrogenase with antibody-coated bacteria in the urine sediment as means of localizing the site of urinary tract infection.

Two noninvasive methods of localizing the site of urinary tract infection, urinary lactic dehydrogenase (LDH) isoenzymes and antibody coating of bacteria in the urinary sediment, have been prospectively compared with the bladder washout technique in a series of children with urinary tract infection. Fifteen children had infection localized in the upper tract. Urinary LDH isoenzymes correctly localized the infection in 14 children; however, the infection was correctly localized by the antibody coating of bacteria in only eight patients (P less than .02). Fourteen children had lower tract infection by the bladder washout technique. Urinary LDH isoenzymes localized the infection in all 14 children, whereas the antibody coating correctly localized the infection in ten children (P less than .05). This study shows the urinary LDH isoenzyme pattern to be a more accurate technique than the detection of antibody-coated bacteria for localizing the site of urinary tract infection.