Plasma neutrophil gelatinase-associated lipocalin predicts renal tubulointerstitial injury in patients with IgA nephropathy

Objective: To investigate the relationship of plasma neutrophil gelatinase-associated lipocalin (pNGAL) and urine neutrophil gelatinase-associated lipocalin (uNGAL) with clinical indicators and pathology in patients with IgA nephropathy (IgAN). Materials and methods: Clinical and pathological data of 36 patients with primary IgAN diagnosed by kidney biopsy were selected. The Oxford and Lee classifications were used to rank the pathology of IgAN patients and the particle-enhanced immunoturbidimetric method was adopted to measure pNGAL and uNGAL. Subsequently, the correlations of pNGAL and uNGAL levels with clinical indices and pathology were analyzed to evaluate the diagnostic value. Results: Referring to the comparison group, pNGAL levels were elevated in the women, 24-hour proteinuria >= 1 g/day, Lee classification IV - V, and tubular atrophy/interstitial fibrosis (T) score of 1 subgroup of Oxford classification (p < 0.05). The pNGAL was positively correlated with 24-hour proteinuria, urine microalbumin, urine alpha 1 microglobulin, and the score of T (p < 0.05), while uNGAL was negatively correlated with serum albumin (p < 0.05). The occurrence of T1 was evaluated by pNGAL, serum creatinine (Scr), 24-hour proteinuria, and estimated glomerular filtration rate (eGFR), and it was shown that the area under the curve of 24-hour proteinuria, pNGAL, Scr, and eGFR were 0.629, 0.817, 0.919, and 0.799, respectively; in addition, the sensitivity of both pNGAL and eGFR are 100%. Conclusion: The pNGAL levels in patients with IgAN are positively correlated with the Lee and Oxford classifications of T scores. The level of pNGAL in IgAN patients is found to be a prominent indicator for identification of renal tubulointerstitial injury and perhaps this feature may make it a non-invasive predictor for progression of IgAN.