Abstract
Abstract
Introduction
Kidney biopsy is the reference tool for diagnosing and guiding treatment strategies in inflammatory renal diseases, such as lupus nephritis (LN).
We investigated the histopathological findings in first-time kidney biopsies from a large cohort of SLE patients. We focused on the occurrence and type of histopathological findings other than LN, and fulfillment of renal criteria in established SLE classification systems were analyzed.
Methods
We retrospectively included SLE patients (n = 139) who underwent a first kidney biopsy between 1995 and 2021, upon clinical suspicion of renal involvement. Based on histology, two groups were defined, LN and non-LN, for which clinical and laboratory features were compared.
Results
Findings consistent with LN according to ISN/RPS classification system were present in 123/139 patients (88.5%) and findings not consistent with LN were present in 16 /139 (11.5%).
Non-LN patients were older at SLE diagnosis compared to LN patients (M, years 38.0 vs. 30.1, p=0.013) and had longer disease duration (M, years 11.9 vs 0.5) (p=0.027).
Among non-LN patients 85.7% met the SLICC criteria item for renal SLE, seen in 94.7% in the LN group (ns). For the ACR/EULAR criteria, 66.7% of the non-LN group fulfilled the criteria compared to 74.8% in LN patients (ns). Proteinuria below the criteria cut-off level (< 0.5 g/24 h) was seen in 20% of patients with class III/IV LN.
Conclusion
Our data confirm the importance of kidney biopsy for ruling out the presence of renal pathology other than LN. Patients with low-grade proteinuria may exhibit severe types of LN, which reinforces the need for early biopsies to detect LN.
Key Points• Our findings show that histopathology changes other than lupus nephritis may occur in a significant number of patients with clinical and laboratory signs of novel kidney involvement.• Low-grade proteinuria does not exclude findings of active lupus nephritis that require the start of immunosuppressive therapy.• The study stresses the importance of performing kidney biopsies also in the presence of low-grade proteinuria or when signs of kidney function abnormalities occur.• This is crucial as early detection and prompt initiation of therapy may improve outcomes in lupus nephritis.
Funder
ALF funding from Region Stockholm
Karolinska Institutet Foundation
The King Gustaf V 80th Birthday Fund
The Swedish Rheumatism Association
The Swedish Kidney Foundation
Stig and Gunborg Westman´s Foundation
Dr Margaretha Nilsson Foundation for medical research
Svenska Sällskapet för Medicinsk Forskning
Karolinska Institute
Publisher
Springer Science and Business Media LLC
Subject
General Medicine,Rheumatology