Glomerulonephritis Evaluation (KDIGO 2021)

Algorithm Steps

1. ▶

   Start

   Suspected Glomerular Disease

   Proteinuria, hematuria, or declining kidney function

   1. ●

      Action

      Initial Laboratory Evaluation

      Comprehensive workup for suspected GN

      • Urinalysis with microscopy (dysmorphic RBCs, RBC casts)
      • Spot urine protein/creatinine ratio (UPCR)
      • Serum creatinine, eGFR
      • Serum albumin
      • Complete metabolic panel
      • CBC with differential
      1. ◆

         Decision

         Clinical Syndrome Classification

         Pattern of presentation guides workup

         • Nephrotic: Proteinuria >3.5g/day, hypoalbuminemia, edema, hyperlipidemia
         • Nephritic: Hematuria (RBC casts), HTN, oliguria, modest proteinuria, AKI
         • Mixed: Features of both
         • Asymptomatic: Isolated hematuria or proteinuria
         1. ●

            Action

            Nephrotic Syndrome Workup

            Additional testing for nephrotic presentation

            • Anti-PLA2R antibody (membranous nephropathy)
            • Hepatitis B and C serologies
            • HIV
            • ANA (lupus nephritis if positive)
            • Serum and urine protein electrophoresis (SPEP/UPEP)
            • Fasting lipids
            • Consider: Light chains, HbA1c
            1. ●

               Action

               Renal Imaging

               Assess kidney size and rule out obstruction

               • Renal ultrasound: Size, echogenicity, obstruction
               • Normal/large kidneys: More likely acute/reversible
               • Small echogenic kidneys: Chronic damage, biopsy may not help
               • Single kidney or other contraindications to biopsy
               1. ◆

                  Decision

                  Kidney Biopsy Indicated?

                  Consider indications and contraindications

                  • Indications:
                  • - Unexplained AKI with active sediment
                  • - Nephrotic syndrome in adults (except DM >10yr + retinopathy)
                  • - Nephritic syndrome with systemic features
                  • - Rapidly progressive GN (RPGN)
                  • Contraindications: Uncontrolled HTN, bleeding diathesis, single kidney (relative)
                  1. ●

                     Action

                     Empiric Management

                     If biopsy not performed/pending

                     • ACEi/ARB for proteinuria (max tolerated dose)
                     • SGLT2i if eGFR allows
                     • Blood pressure control <130/80
                     • Edema management (diuretics)
                     • Statin for hyperlipidemia
                     • DVT prophylaxis if severe nephrotic
                     1. ✓

                        Outcome

                        Remission/Stable

                        Monitor for relapse, continue nephroprotection

                  2. ●

                     Action

                     Proceed with Kidney Biopsy

                     Gold standard for GN diagnosis

                     • Pre-biopsy: Check BP, coagulation, consent
                     • Light microscopy, immunofluorescence, electron microscopy
                     • Provides: Diagnosis, activity vs chronicity, prognosis
                     • Post-biopsy: Observe 6-24h, check Hgb
                     1. ●

                        Action

                        Interpret Biopsy Results

                        Common diagnoses by pattern

                        • Nephrotic pattern: MCD, FSGS, Membranous, Diabetic
                        • Nephritic pattern: IgAN, Lupus nephritis, ANCA GN, Anti-GBM
                        • MPGN pattern: Consider cryoglobulinemia, C3 glomerulopathy
                        • Activity index guides intensity of treatment
                        • Chronicity index indicates irreversible damage
                        1. ●

                           Action

                           Disease-Specific Treatment

                           Tailored to biopsy diagnosis

                           • MCD: High-dose steroids (responds well)
                           • FSGS: Steroids, calcineurin inhibitors if refractory
                           • Membranous: Rituximab or CNI if anti-PLA2R+
                           • IgAN: Optimize RAAS blockade, consider steroids if high risk
                           • Lupus nephritis: MMF or cyclophosphamide + steroids
                           • ANCA vasculitis: Rituximab or cyclophosphamide + steroids
                           1. ✓

                              Outcome

                              Refractory/Progressive

                              Consider alternative agents, clinical trial, transplant evaluation

                  3. ⚠

                     Warning

                     RPGN Suspected?

                     Rapidly progressive GN is an emergency

                     • Features: AKI over days-weeks, active sediment, HTN
                     • Causes: ANCA vasculitis, anti-GBM, lupus, PIGN
                     • Consider empiric steroids while awaiting biopsy
                     • Urgent nephrology consultation
                     • May need plasma exchange (anti-GBM, severe ANCA)
         2. ●

            Action

            Nephritic Syndrome Workup

            Additional testing for nephritic presentation

            • Complement levels (C3, C4)
            • ANCA (MPO, PR3)
            • Anti-GBM antibody
            • ANA, anti-dsDNA
            • ASO titer (post-streptococcal)
            • Blood cultures if concern for endocarditis
            • Cryoglobulins