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Q1: Definition, classification and complement split (3 min)
Examiner: Define nephritic syndrome and explain how you classify its causes. Candidate: Nephritic syndrome is the clinical expression of glomerular inflammation: haematuria with dysmorphic red cells and red-cell casts, subnephrotic proteinuria, hypertension, oedema and an acute rise in creatinine (AKI). The pivotal bedside discriminator is the serum complement. Low-complement causes (mnemonic PSLICE) are Post-streptococcal GN, SLE/lupus, subacute bacterial endocarditis, Infectious/shunt nephritis, and Cryoglobulinaemia, plus membranoproliferative GN and C3 glomerulopathy. Normal-complement causes are IgA nephropathy (the commonest primary GN worldwide), IgA vasculitis (Henoch-Schonlein purpura), anti-GBM disease and ANCA-associated vasculitis. RPGN is classified histologically by immunofluorescence: Type I linear anti-GBM, Type II granular immune-complex (lupus, post-infectious, IgA), Type III pauci-immune (ANCA-associated).
Q2: Post-streptococcal GN — mechanism and management (3 min)
Examiner: Walk me through the pathogenesis of post-streptococcal GN and its management. Candidate: Nephritogenic group A streptococcal M types (1, 2, 4, 12 for pharyngitis; 2, 49, 55, 57, 60 for pyoderma) carry antigens SpeB and NAPlr that deposit in glomeruli, form subepithelial humps, activate complement via the alternative and lectin pathways (low C3 with normal C4), and trigger diffuse endocapillary proliferative GN. PSGN presents 1 to 3 weeks after pharyngitis or 2 to 4 weeks after pyoderma. C3 normalises within 6 to 8 weeks; persistence beyond that mandates biopsy. Management is supportive and self-limiting: salt and fluid restriction, loop diuretic for oedema, gradual BP control with labetalol or nicardipine for hypertensive emergency, hyperkalaemia management, and a 10-day course of oral penicillin V to clear the organism (does not change the GN course). Prognosis is excellent in children; dialysis rarely required (AEIOU criteria).
Q3: Rapidly progressive GN and pulmonary-renal syndromes (3 min)
Examiner: A 45-year-old man presents with rapidly progressive AKI, haemoptysis and anti-GBM antibody. Talk me through the emergency management. Candidate: This is anti-GBM disease (Goodpasture) presenting as a pulmonary-renal syndrome — a medical emergency. The pathogenic antibody is IgG against the non-collagenous domain of the alpha-3 chain of type IV collagen (alpha3(IV)NC1) in the GBM and alveolar basement membrane, producing linear IgG on IF and crescents on light microscopy. Management is triple therapy: (i) plasma exchange — daily or alternate-day 4 L exchanges with 5% albumin (and fresh frozen plasma if bleeding), continued until anti-GBM antibody is undetectable (typically 2 to 3 weeks); (ii) methylprednisolone pulse 500 to 1000 mg IV daily for 3 days then oral prednisolone 1 mg/kg/day tapering; and (iii) cyclophosphamide 2 mg/kg/day orally (dose-reduce for age and renal function) for 2 to 3 months to suppress further antibody production. PJP prophylaxis with co-trimoxazole is given throughout. Transplantation is deferred until anti-GBM antibody has been negative for at least 6 months. The same pulmonary-renal picture with ANCA positivity (and negative anti-GBM) is treated as ANCA vasculitis — rituximab or cyclophosphamide plus steroids, with plasma exchange if dialysis-dependent or severe pulmonary haemorrhage (MEPEX).
Q4: ANCA vasculitis subtypes and treatment (2 min)
Examiner: Distinguish the ANCA-associated vasculitides and outline induction therapy. Candidate: Three subtypes: granulomatosis with polyangiitis (GPA, formerly Wegener) — anti-PR3 (cytoplasmic c-ANCA), granulomatous ENT and lung disease (sinusitis, saddle nose, pulmonary nodules/cavities, subglottic stenosis); microscopic polyangiitis (MPA) — anti-MPO (perinuclear p-ANCA), renal-predominant with pulmonary haemorrhage (no granulomatous ENT disease), mononeuritis multiplex; eosinophilic granulomatosis with polyangiitis (EGPA, Churg-Strauss) — adult-onset asthma, eosinophilia, sinusitis, mononeuritis multiplex, anti-MPO in about 40%. Induction is methylprednisolone pulse then oral prednisolone 1 mg/kg/day PLUS rituximab 375 mg/m2 weekly for 4 weeks (RAVE trial: non-inferior to cyclophosphamide and superior in relapsing disease) OR cyclophosphamide 15 mg/kg IV every 2 weeks for 3 doses then every 3 weeks. Plasma exchange (MEPEX) for severe renal failure (creatinine over 5.7 mg/dL or dialysis-dependent) or diffuse alveolar haemorrhage. PJP prophylaxis with co-trimoxazole. Maintenance is rituximab 1 g every 4 to 6 months for 18 to 24 months.
Q5: Lupus nephritis — classification and treatment (2 min)
Examiner: How do you classify and treat lupus nephritis class IV? Candidate: The ISN/RPS 2003 classification has six classes. Class IV diffuse proliferative (over 50% of glomeruli with active/chronic lesions) is the most nephritic and severe — low C3 AND C4, ANA and anti-dsDNA positive, full-house immunofluorescence (IgG, IgA, IgM, C3, C1q, C4), wire-loop deposits on light microscopy. Induction (3 to 6 months): mycophenolate mofetil 2 to 3 g/day OR low-dose IV cyclophosphamide (Euro-Lupus 500 mg every 2 weeks for 6 doses) PLUS glucocorticoids (methylprednisolone pulse then prednisolone 0.5 to 0.8 mg/kg/day tapering), with voclosporin 23.7 mg twice daily (AURORA 1 and 2) or tacrolimus as triple therapy, and hydroxychloroquine 200 to 400 mg daily throughout. Maintenance: MMF 1 to 2 g/day or azathioprine 1 to 2 mg/kg/day plus low-dose prednisolone, hydroxychloroquine indefinitely. Ten-year renal survival is 80 to 90% with modern therapy.
Q6: High-yield exam pearls (2 min)
Examiner: Give me five high-yield pearls for nephritic syndrome. Candidate: (1) RBC casts = glomerular bleeding — the single most discriminating microscopy finding. (2) Low complement (PSLICE): post-strep GN, SLE, subacute endocarditis, infectious/shunt, cryoglobulinaemia — plus MPGN and C3G. Normal complement: IgA nephropathy (commonest primary GN), IgA vasculitis/HSP, anti-GBM, ANCA vasculitis. (3) PSGN: 1 to 3 weeks after pharyngitis, low C3 normalising by 6 to 8 weeks, supportive and self-limiting in children. (4) RPGN = crescents on biopsy — a renal emergency; treat with urgent steroids plus cyclophosphamide or rituximab, plus plasma exchange for anti-GBM and severe ANCA. (5) Pulmonary-renal syndrome: anti-GBM (Goodpasture) and ANCA vasculitis — plasma exchange plus steroids plus cyclophosphamide or rituximab.