The Role of Tc-99m-DTPA Nuclear Medicine GFR Studies in Pediatric Solid Tumor Patients

BACKGROUND: Technetium-99m-diethylene-triamine-pentaacetate (Tc-99m-DTPA) nuclear medicine studies allow for accurate monitoring of glomerular filtration rate (GFR) in cancer patients receiving chemotherapy. However, these scans may be logistically challenging and are associated with some radiation exposure. OBJECTIVES: The purpose of this study was to retrospectively review the use of Tc-99m-DTPA studies to evaluate the subgroup of children with low GFR by Tc-99m-DTPA who may most benefit from this procedure-namely, the patients with a normal serum creatinine (SCr) and GFR estimated by Schwartz (Sch) calculation who may otherwise not have their renal dysfunction recognized. We further determined how the GFR result modified the treatment plan for these patients. METHODS: Patients aged 2 to 18 years with solid tumors diagnosed from 2000 to 2007 were identified. Tc-99m-DTPA results, corresponding height and SCr, were recorded and GFR Sch calculated. The clinical course of patients with Tc-99m-DTPA <80 mL/min/1.73 m and a normal SCr and GFR Sch were reviewed in detail. RESULTS: Of 714 Tc-99m-DTPA studies in 231 patients, 41 (5.7%) in 24 patients (10.4%) reported a GFR result of <80 mL/min/1.73 m. Of those 41 studies, 16 (39%, 13 patients) were associated with normal SCr and normal GFR Sch. Of these 13 patients, 11 (85%) had 1 or more clinical risk factors suggestive of preexisting renal disease. Three patients had modifications to their chemotherapy. CONCLUSIONS: There were few abnormal Tc-99m-DTPA results reported in this population. The majority of patients with abnormal Tc-99m-DTPA studies and normal SCr had clinical risk factors for renal dysfunction. A future prospective study may better help to define oncology patients for whom Tc-99m are essential for estimating renal function.