When could the administration of furosemide be avoided?

PURPOSE: The purpose of this study was to evaluate whether some parameters of the basic renogram allow one to omit the administration of furosemide in cases of hydronephrosis.
MATERIALS AND METHODS: One hundred thirty-seven children (274 kidneys) referred for uni- or bilateral hydronephrosis were evaluated retrospectively. In all children additional furosemide challenges followed by postmicturition views were acquired because of unsatisfactory renal emptying. The patients were categorized into 2 groups according to the residual renal activity on the postmicturition view: those with good emptying (R-) of both kidneys, for which the administration of furosemide was considered of no influence, and those with partial or no emptying of at least 1 kidney (R+). The renogram parameters chosen for predicting R+ and R- were time to maximum (Tmax), output efficiency at 20 minutes (OE20), and normalized residual activity at 20 minutes (NORA20). For each parameter, the number of children was then calculated, for whom the administration of furosemide could have been omitted.
RESULTS: A total of 112 children were categorized as R- and 25 as R+. The cutoff values for 100% negative predictive value of Tmax, OE20, and NORA20 were 4.5 minutes, 66%, and 1.45 respectively. Application of these cutoff values for the parameters yields, in retrospect, 6 (4%), 29 (21%), and 22 (16%) children respectively for whom administration of furosemide could have been omitted.
CONCLUSION: On the basis of OE20 and NORA20, the administration of furosemide could have been omitted in a substantial number of patients, despite unsatisfactory renal emptying on the basic renogram.