LCN2 and sexually transmitted disease: The levels of serum and urinary NGAL were significantly higher in the VD group than in the nVD group (serum NGAL, 420.25 ± 45.18 ng/mL vs. 314.68 ± 41.08 ng/mL, p = 0.036; urinary NGAL, 420.87 ± 38.12 ng/mL vs. 250.84 ± 39.45, p = 0.002; Figure 2).