Do Young Kim

Background To determine whether urine neutrophil gelatinase-associated lipocalin (uNGAL) might be superior to pyuria for detecting urinary tract infection (UTI) regardless of urine specific gravity (SG) in young children. Methods We conducted a retrospective analysis of children aged < 3 years who were evaluated for UTI with urinalysis, urine culture, and uNGAL measurements during a 5-year period. Sensitivity, specificity, likelihood ratios (LRs), predictive values (PVs), area under the curves (AUCs) of uNGAL cut-off levels, and various microscopic pyuria thresholds for detecting UTI were calculated for dilute (SG < 1.015) and concentrated urine (SG ≥ 1.015). Results Of 456 children included, 218 had UTI. The diagnostic value of urine white blood cell (WBC) concentration to define UTI changed with urine SG. For detecting UTI, uNGAL cut-off of 68.4 ng/mL had higher AUC values than pyuria ≥ 5 WBCs/high power field (HPF) for dilute and concentrated urine samples (both P < 0.05). Positive LR and PV and specificity of uNGAL were all greater than those of pyuria ≥ 5 WBCs/HPF regardless of urine SG, although the sensitivity of pyuria ≥ 5 WBCs/HPF was higher than that of uNGAL cut-off for dilute urine (93.8% vs. 83.5%) (P < 0.05). At uNGAL ≥ 68.4 ng/mL and ≥ 5 WBCs/HPF, posttest probabilities of UTI were 68.8% and 57.5% for dilute urine and 73.4% and 57.3% for concentrated urine, respectively. Conclusions Urine SG can affect the diagnostic performance of pyuria for detecting UTI and uNGAL might be helpful for identifying UTI regardless of urine SG in young children. Graphical abstract A higher resolution version of the Graphical abstract is available as Supplementary information

The messenger RNA-based vaccine for the coronavirus disease 2019 (COVID-19) may induce glomerulonephritis, including immunoglobulin A nephropathy (IgAN). New-onset IgAN triggered by vaccination against COVID-19 has been reported rarely, especially in children. Herein, we report a pediatric case of newly diagnosed IgAN after administration of the Pfizer vaccine for COVID-19. A 12-year-old girl was referred to our hospital for evaluation of gross hematuria after inoculation with the second dose of Pfizer’s COVID-19 vaccine; she had no adverse effects after the first dose. At the time of admission, she showed heavy proteinuria and persistent hematuria. Kidney biopsy revealed an IgAN, and she was treated with an oral steroid and an angiotensin-converting enzyme inhibitor. Four months after discharge, the proteinuria and hematuria resolved completely.