Role of Repeat Kidney Biopsy in Lupus Nephritis in a Uruguayan Cohort

Background: There is no biomarker that substitutes renal biopsy in assessment of histopathological class, activity, or chronicity in lupus nephritis (LN). We aim to characterize clinical and histological features of repeat biopsies by clinical indication in LN. Methods: We reviewed the clinical charts and pathology reports of patients with LN and two renal biopsies from a University Hospital in Uruguay. Results: A total of 20 patients, 18 women were analyzed. Clinical characteristics are shown in Table 1. In 5/9 patients biopsied because of mild clinical changes (hematuria and/or sub-nephrotic proteinuria), pathology revealed severe proliferative forms. Repeat biopsy showed a change in LN class in 80% of the sample, 18.2% to a lower class, 35% to a higher class and 30% had an additional membranous pattern (Class IV+V). There was also an increase in interstitial fibrosis and tubular atrophy (IFTA), 5 vs 20% (p 0.019) and the presence of moderate-severe IFTA was associated with lower eGFR after initial treatment (p 0.009). After repeat biopsy immunosuppression was intensified in 17 patients (85%). Conclusion: Change in LN class was frequent in this cohort and there was a significant increase in chronic changes in repeat biopsies with a negative impact in renal function. Repeat biopsy by clinical indication is a valuable tool in LN management. Baseline characteristics according to first and second biopsy - First biopsy Second biopsy p value Age at time of the biopsy (y), mean (SD) 26.2±11.5 33.1±11.7 <0.0001 Microscopic hematuria and/or proteinuria, n(%) 5 (25) 4 (20) 0.705 Nephrotic syndrome, n (%) 10 (50) 12 (60) 0.525 Nephritic syndrome, n (%) 1 (5) 0 --- RPGN, n (%) 3 (15) 3 (15) --- LN Class I/II, n (%) 3 (15) 3 (15) --- LN Class III, n (%) 4 (20) 1 (5) --- LN Class IV, n (%) 11 (55) 8 (40) --- LN Class V, n (%) 2 (10) 2 (10) --- LN Class III/IV+V, n (%) 0 6 (30) --- Creatinine (mg/dl), median (IQR) 1.08 (0.70-1.45) 1.00 (0.70-1.40) 0.730 eGFR (ml/min/1.73m2), median (IQR) 72.7 (51.7-111.8) 73.7 (46.6-118.5) 0.988 Proteinuria (g/24hs), median (IQR) 3.94 (2.35-6.40) 4.29 (2.56-6.25) 0.883 Initial treatment Corticosteroids 20 (100) 19 (100) --- Cyclophosphamide 11 (55) 10 (52.6) --- Mycophenolate 2 (10.1) 10 (52.6) 0.001 Azathioprine 6 (30) 1 (5) 0.001