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Glomerulonephritis and the nephritic syndrome
The nephritic syndrome is inflammation of the glomeruli with haematuria and red cell casts, hypertension and oedema; the deciding step is the complement level (C3): low points to post-streptococcal disease, lupus or MPGN, and normal to IgA, ANCA or anti-GBM disease.
Why it matters in the exam
Nephritic questions are almost always built on a timeline and serology. Haematuria within 1–3 days of a sore throat points to IgA nephropathy, while haematuria 1–3 weeks after a sore throat (or several weeks after a skin infection) with a low C3 points to post-streptococcal glomerulonephritis. When kidney function falls rapidly over days to weeks (RPGN, with crescents on biopsy), it is divided into three types by immunofluorescence: linear (anti-GBM), granular (immune complexes) and pauci-immune (ANCA).
Exams especially like the combination of lung haemorrhage with glomerulonephritis (pulmonary-renal syndrome), where the options are anti-GBM disease (Goodpasture) and ANCA vasculitis — both emergencies that need steroids and immunosuppression, and in some cases plasma exchange. GPA is characterised by c-ANCA (PR3) with upper airway involvement (sinusitis, a perforated nasal septum), MPA by p-ANCA (MPO), and EGPA by asthma and eosinophilia. Lupus with low C3 and C4 and anti-dsDNA antibodies needs a biopsy and classification by class. In most cases the exam question does not require recall of every classification but the right decision: order complement and serology, recognise an emergency, and not delay treatment in a patient whose kidney function is falling day by day.
Key points
- Nephritic: haematuria with RBC casts, hypertension, oedema and protein below the nephrotic range.
- Low C3: post-streptococcal, lupus, MPGN; normal C3: IgA, ANCA, anti-GBM.
- IgA: days after an infection; post-streptococcal: 1–3 weeks.
- RPGN: linear (anti-GBM), granular (immune complexes), pauci-immune (ANCA).
- Lung haemorrhage + nephritis: anti-GBM or ANCA — an emergency, steroids and immunosuppression.
Summary table
| Disease | Clue | Serology / complement | Treatment |
|---|---|---|---|
| IgA nephropathy | Haematuria 1–3 days after a sore throat | Normal C3 | ACEi/ARB, SGLT2 inhibitor; steroids if high risk |
| Post-streptococcal | 1–3 weeks after a sore throat, cola-coloured urine | Low C3, positive ASO or anti-DNase B | Supportive: diuretics, treat hypertension |
| Anti-GBM (Goodpasture) | Lung haemorrhage + RPGN | Anti-GBM; linear IgG on biopsy | Plasma exchange, steroids, cyclophosphamide |
| ANCA vasculitis | Sinusitis, septal perforation (GPA); asthma (EGPA) | c-ANCA/PR3 or p-ANCA/MPO; normal C3 | Steroids + rituximab or cyclophosphamide |
| Lupus nephritis | Young woman, rash, joint pain | ANA, anti-dsDNA; low C3 and C4 | Biopsy; class III–IV: steroids + mycophenolate or cyclophosphamide |
A free exam question
לאיזה מהמחלות הכלייתיות הבאות יתכן ו- Eculizumab ?מהווה טיפול אפשרי (the question as examined, in Hebrew)
- א. Membranous Glomerulonephritis
- ב. ANCA-Associated Glomerulonephritis
- ג. Systemic Lupus Erytematosus Type IV
- ד. C3 Glomerulonephritis
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Sources
- KDIGO Clinical Practice Guideline for the Management of Glomerular Diseases, 2021 — IgA nephropathy; infection-related GN; ANCA-associated vasculitis; anti-GBM disease; lupus nephritis
- Harrison's Principles of Internal Medicine, 21st edition (2022) — Glomerular Diseases
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-02. The text may contain errors; when in doubt, check the source.