Massive Proteinuria-Induced Injury of Tubular Epithelial Cells in Nephrotic Syndrome is Not Exacerbated by Furosemide

Background/Aims: Massive proteinuria, a significant sign of nephrotic syndrome (NS), has the potential to injure tubular epithelial cells (TECs). Furosemide is widely used for the treatment of edema, a common manifestation of NS. However, whether furosemide treatment affects massive proteinuria-induced TEC injury in patients with NS is unknown. Methods: The effect of furosemide on TEC damage was investigated in vitro . In addition, a clinical study was conducted to study whether the short-term treatment of nephrotic edema with furosemide could exacerbate TEC injury. Results: The proliferation of in vitro human kidney-2 (HK-2) cells exposed to massive urinary protein (8 mg/mL) significantly decreased ( P P n =13) received furosemide (60-120 mg/day, intravenously) for 1 week; the remaining participants (control group) did not receive furosemide or any other diuretics. The results showed that the 24-h urine volume in the furosemide-treated group was slightly, but not significantly, higher than that in the control group ( P >0.05). In addition, serum levels of BUN, Scr, Cys C, and urinary Kim-1 and NGAL were not significantly different between the two groups (all P >0.05). Twenty-three patients underwent a renal biopsy. Of these, 22 patients exhibited vacuolar degeneration of the TECs; 8 patients showed brush border membrane shedding of the TECs; and 12 patients showed protein casts. However, there were no significant differences between the two groups (all P >0.05). Conclusion: In summary, massive proteinuria induced the injury of TECs in patients with NS, and furosemide treatment did not aggravate this injury.