Routine blood test monitoring of complete blood count (CBC), serum electrolytes, or creatinine is not warranted for young children receiving long-term prophylaxis with trimethoprim-sulfamethoxazole (TMP-SMZ) for recurrent urinary tract infections (UTIs), investigators concluded in a paper published in Clinical Pediatrics.
Milan Dattaram Nadkarni, MD, of Wake Forest University in Winston-Salem, North Carolina, and colleagues analyzed data from the prospective randomized, placebo-controlled RIVUR trial, which enrolled 607 children aged 2 to 71 months who had vesicoureteral reflux (VUR) diagnosed after symptomatic UTIs. In that trial, investigators randomly assigned 302 patients to receive TMP-SMZ and 305 to receive placebo and followed up with patients for 24 months.
Investigators measured CBC, serum electrolytes, and creatinine at baseline and at the 24-month study conclusion. Dr Nadkarni’s team reported finding no significant hematologic, electrolyte, or renal abnormalities between the treatment and placebo groups.
“In conclusion, our study did not reveal any adverse effect of TMP-SMZ prophylaxis on CBC, serum electrolytes, and creatinine,” the authors concluded. “As a result, we do not recommend any such routine laboratory tests in otherwise healthy children who are on long-term prophylaxis with TMP-SMZ for VUR or any other medical condition.”
The large number of patients who received TMP-SMZ in a prospective, randomized controlled trial was a strength of the study, Dr Nadkarni’s team stated. The study had limitations, however. Laboratory abnormalities were a secondary end point and local laboratories rather than a single center performed the tests, and laboratory tests often were ordered at the discretion of treating physicians. Some patients refused to have follow-up laboratory tests, resulting in missing laboratory values.
Nadkarni MD, Mattoo TK, Gravens-Mueller L, et al. Laboratory findings after urinary tract infection and antimicrobial prophylaxis in children with vesicoureteral reflux [published online December 31, 2019]. Clin Pediatr.