Usefulness of 99mTc-dimercaptosuccinic acid renal scan in the diagnosis and follow-up of acute tubulointerstitial nephritis in children

BACKGROUND Symptoms and signs of acute tubulointerstitial nephritis (ATIN) are nonspecific; therefore, renal biopsy is often necessary to clarify the diagnosis. The aim of this study was to evaluate the use of 99mTc-dimercaptosuccinic acid (DMSA) scintigraphy in the diagnosis and follow-up of ATIN. METHODS We retrospectively reviewed the charts of five patients (nine renal units) with a median age of 14 years who underwent DMSA scan after a clinical and/or biopsy-proven diagnosis of ATIN. The exam was performed within 1 month after disease onset and repeated at a median time of 12 months after the acute phase. RESULTS DMSA renal scans performed during the acute phase allowed the discovery of suggestive findings, including diffuse reduction of the renal uptake of radionuclide and presence of multiple 'cold' focal lesions in a corticomedullary distribution. The follow-up scintigraphy resulted normal in two patients who were treated with steroids and in one patient who presented a mild renal dysfunction in the acute phase. By contrast, the control scan showed persistent renal damage in one patient who was further readmitted because of hypertension and in one renal transplanted patient who presented a Stage 3 acute kidney injury in the acute phase. CONCLUSIONS DMSA renal scan might be a reliable tool for an early non-invasive diagnosis of ATIN in children and might be particularly useful in those patients who are not candidates for a kidney biopsy. Moreover, DMSA scan gives accurate follow-up evaluation, as it allows monitoring of the evolution of acute renal parenchymal inflammation with potential risk of renal scar formation. Due to the small sample size, our findings warrant further validation in a larger study.