622 Baseline inflammatory indexes and clinicopathological features to predict the outcome of acute interstitial nephritis

Abstract Backgrounds-and-aims Acute tubulointerstitial nephritis(AIN) is a rare cause of acute kidney injury(AKI). We aimed to investigate the characteristics of AIN patients and predictive factors for treatment response. Method 31 patients diagnosed with AIN by biopsy between 2006-2021 were included in this retrospective study. Baseline clinical, pathological, and laboratory findings, including CBC(complete blood count), creatinine, serum-immune-inflammation-index(SII), neutrophil-to-lymphocyte ratio(NLR), and platelet-to-lymphocyte ratio(PLR) were evaluated. Also, treatment response and creatinine levels at the last follow-up were noted. Results Median age was 46 years, and 80.6% of the patients were female. Median baseline creatinine and proteinuria levels were 4.1 mg/dL and 0.84 g/g or g/day. Median follow-up was 14 months. 93.5% of patients received immunosuppressives. End-stage-kidney-disease(ESKD) developed in five patients. Renal recovery(creatinine < 1.4 mg/dL) was observed in 17 (54.8%) patients. Global glomerulosclerosis percentage, interstitial fibrosis(IF), tubular atrophy(TA), granuloma formation, and higher baseline hemoglobin levels were associated with poor renal outcomes(non-responder). Also, ESKD-developed patients had higher baseline hemoglobin(p = 0.033) and lymphocyte(p = 0.044) and lower PLR levels(p = 0.016), as well as higher degrees of global glomerulosclerosis(p = 0.014), IF(p = 0.042), and TA(p = 0.030). Conclusion Treatment rates are low for AIN, which may lead to ESKD. Besides chronicity in pathology specimens, higher baseline hemoglobin levels and lower PLR might be prognostic for AIN. Further studies should be conducted on new markers for AIN. Table: Baseline clinical/laboratory/pathology and treatment data of responder(last serum creatinine < 1.4 mg/dL) and non-responder groups. No Response Responder Parameters (n = 14) (n = 17) p-value Age, median (min-max) 44 (21-61) 44.5 (17-71) 0.874 Sex, F/M 10/4 15/2 0.370 Creatinine (mg/dl) 3.8 (2.4-9.1) 4.32 (1.03-11.2) 0.677 eGFR (CKD-EPI) 16.9 (4.7-32) 11.29 (3.69-70) 0.525 Albumin, mean ± std 3.9 ± 0.8 4.0 ± 0.4 0.573 Hgb 11.8 (6.9-13.8) 9.75 (7.2-11.7) 0.029 Lymph 1400 (400-3300) 1180 (500-1700) 0.140 Neutroph 6500 (3100-24700) 5650 (3270-9900) 0.665 Plt 280000 (75000-645000) 291500 (148600-507000) 0.733 Eos 200 (0-700) 135 (0-300) 0.151 SII 1400 (513.6-5689.8) 1635 (495.7-4563) 0.603 NLR 4.88 (2.3-17.6) 4.97 (2.6-12.6) 0.603 PLR 194.3 (124.2-1123.5) 302.26 (151.6-460.9) 0.225 P