#5414 CLINICAL UTILITY OF SEROLOGICAL TEST AT TIME OF BIOPSY

Abstract Background and Aims It is common practice to order serological tests at time of renal biopsy, but the diagnostic value in different clinical settings largely unknown. We utilized data from national Swedish Renal Biopsy Registry analyze positive negative post-test likelihood four diagnoses depending on results frequently used tests. Method Data all biopsies performed during period 2015-01-01 – 2020-12-31 was retrieved Registry. All are classified into one following five biopsy indications: nephrotic syndrome (nephrosis), acute/subacute nephritic (nephritis), other acute kidney injury (AKI), chronic disease stage 1-2 (CKD 1-2), CKD 3-5. given as SNOMED codes by pathologist a diagnosis using ERA coding system nephrologist. Results were analyzed: C3, C4, ANA, anti-dsDNA, ANCA (PR3 and/or MPO-ANCA) anti-phospholipid antibodies. Pre-test likelihood, (PPL) (NPL) for IgA nephropathy (IgAN), diabetic (DN), ANCA-associated vasculitis (AAV) lupus nephritis (LN) analyzed. The yield defined ratio between PPL NPL. Out total 3165 individuals that had undergone there 694 (21.9%) patients assigned IgAN, 378 (11.9%) with DN, 342 (10.8%) AAV 117 (3.7%) LN. proportion being tested varied 17% antibodies 77% ANCA. highest found PPL/NPL 154. In nephrosis went up 290 mainly because very low NPL (0.2%). next best seen SLE both ANA anti-dsDNA exhibited 26. when indication where 33% 0.54% 61. For AKI 46 (PPL 55%, 1.1%). test make less likely nephropathy. never any 42 this diagnosis, however same result slightly increased AAV. A C3(reduced levels) also reduced av nephropathy, / 13. C4 being, hand, IgAN range. Conclusion While utility ANCA, well known, it known substantially disease. Here we present showing C3 decreases while much affected C4. opposite Is IgAN.