Uncommon cases of crescentic glomerulonephritis with preserved renal function at diagnosis: A retrospective case series from a single center.

Background: The aim of this study is to investigate the clinicopathologic characteristics, treatment and prognosis of crescentic glomerulonephritis (Crescentic GN) in patients with normal renal function at diagnosis, and compare to those with impaired renal function.

Methods: We conducted a retrospective review of patients with renal biopsy proven Crescentic GN at our center and divided them into normal eGFR group (eGFR≥60 ml/min/1.73 m) and low eGFR group (eGFR <60 ml/min/1.73 m). Clinical and renal pathological findings at diagnosis and renal outcomes were compared between the two groups using t-test, Wilcoxon rank sum test or Kruskal-Wallis H test.

Results: From Jan 2010 to Dec 2021, 90 Crescentic GN patients with normal eGFR were included, in which clinicopathological diagnoses were LN (lupus nephritis) (60 cases, 66.77 %), IgAN (IgA nephropathy) (9 cases, 10 %), HSPN (Henoch-Schnlein purpura nephritis) (14 cases, 15.6 %) and AAV (ANCA-associated GN) (7 cases, 7.8 %). Compared with the low eGFR group (n = 300), the following characteristics were observed in the normal eGFR group: younger age (p < 0.001), female predominance (p < 0.001), longer time from onset to biopsy (p < 0.001), lower hypertension rate (p < 0.001), lower rate of oliguria (p < 0.001), and anemia (p < 0.001), lower levels of C3 (p < 0.001), C4 (p < 0.001) and Urine RBC (p < 0.001), higher titers of ANA (p < 0.001) and ds-DNA (p = 0.002), lower positive rate of ANCA (<0.001) and GBM (p = 0.02), less extra-renal involvement (p < 0.05), lower proportions of crescents (56.3(51.8-62.7) % vs 66.7 (56.3-81.3) %, p < 0.001) and glomerular sclerosis (p < 0.001), less severe tubulointerstitial lesion (p < 0.001) and interstitial inflammation (p < 0.001), higher degree of immune complex deposition of IgA, IgM, C3, C4 and C1q by Immunofluorescence. Normal eGFR group received lower frequency of intravenous methylprednisolone pulse therapy (71.2 % vs 89 %, p = 0.044) and dialysis treatment (0 % vs 53.7 %, p < 0.001). The 5- and 10-year cumulative renal survival rates from ESRD were 90.7 % vs 45.5 % and 58.3 % vs 43.7 %, respectively in normal and low eGFR group.

Conclusion: Crescentic GN may present with normal renal function, which has poor renal outcomes and may benefit from intensive immunosuppressive treatment. This often occurs in patients with abnormal immunological indicators and systemic autoimmune disease. Shorter time from onset to biopsy may help better management and improve long-term outcomes in these cases. Renal biopsy remains the diagnostic gold standard when urinary abnormalities are present in nephritis.