Abstract
A 13-year-old girl developed a fever, and on the second day of illness was prescribed an antibacterial agent and Loxoprofen. Despite two changes of the antibacterial agent, intermittent fever persisted for 16 days, necessitating admission to our hospital. Laboratory data indicated anemia, and elevation of both the leukocyte count and total serum IgE level. All tests for infections and autoantibodies gave negative results. Urinalysis revealed sterile pyuria, with mild increases in the urinary protein/creatinine ratio and β2-microglobulin level. A midstream urine culture was negative. Gallium-67 scintigraphy gave a false-negative result in both kidneys. However, abdominal contrast-enhanced computed tomography demonstrated multiple spherical filling defects in both kidneys and diffusion-weighted magnetic resonance imaging showed patchy abnormal high intensity in the bilateral renal parenchyma. Therefore, we performed percutaneous renal biopsy, and acute tubulointerstitial nephritis was diagnosed. The patient had taken all of the antibacterial agents prescribed several times, whereas Loxoprofen had been taken twice for the first time. A drug lymphocyte stimulation test for Loxoprofen showed a positive response. Abdominal diffusion-weighted magnetic resonance imaging may be very useful for early diagnosis and treatment of NSAIDs-induced acute tubulointerstitial nephritis.
