Paeds · nephrology-urology-fluids-and-electrolytes
Post-infectious glomerulonephritis
Also known as PSGN · Post-streptococcal glomerulonephritis · Acute postinfectious glomerulonephritis · Diffuse endocapillary proliferative glomerulonephritis · Postinfectious GN
Fellowship guide to post-infectious glomerulonephritis (PSGN): the classic acute nephritic syndrome that follows group A streptococcal pharyngitis by one to three weeks or skin infection by three to six weeks, defined by smoky haematuria, oedema, and hypertension with a low C3 and normal C4 that recovers within eight weeks; the immune-complex and complement pathophysiology with subepithelial humps; the supportive management of fluid restriction, diuretics, and antihypertensives plus streptococcal eradication; and the excellent prognosis in children, with the atypical features that mandate renal biopsy.
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Red flags
- A school-aged child with smoky or cola-coloured urine, periorbital oedema, and hypertension one to three weeks after a sore throat
- Seizures, headache, or visual disturbance signalling hypertensive encephalopathy from undiagnosed PSGN
- Pulmonary oedema and respiratory distress from salt and water retention in acute nephritic syndrome
- Rapidly rising creatinine with oliguria or crescents suggesting a rapidly progressive rather than typical PSGN course
- Persistent low C3 beyond eight weeks pointing away from PSGN toward C3 glomerulopathy, MPGN, or lupus nephritis
- Nephrotic-range proteinuria, low C4, or no streptococcal evidence flagging an alternative glomerulonephritis needing biopsy
- Severe hyperkalaemia or acidosis from acute kidney injury requiring urgent renal replacement therapy
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- Recognises the acute nephritic syndrome of post-streptococcal glomerulonephritis with smoky haematuria, oedema, and hypertension
- Requests a low C3 with normal C4 and streptococcal serology to confirm the diagnosis
- Initiates supportive care with fluid and salt restriction, diuretics, and antihypertensives
- Explains the immune-complex and alternative-complement pathophysiology with subepithelial humps
- Identifies the atypical features that mandate renal biopsy and rule out C3 glomerulopathy and lupus nephritis
- Counsels families on the excellent prognosis and the expected recovery of C3 within eight weeks
- Definition and clinical triad of post-streptococcal glomerulonephritis
- The one to three week post-pharyngitis and three to six week post-impetigo latency
- Low C3 with normal C4 recovering by eight weeks, and supportive management
- Manages the complications of hypertensive encephalopathy, pulmonary oedema, and acute kidney injury
- Communicates the diagnosis, the role of streptococcal eradication, and the prognosis to families
- Recognises the atypical case needing nephrology referral and biopsy
- Level 1: Recognition of the acute nephritic presentation and the streptococcal link
- Level 2: Interpretation of low C3 with normal C4 and initiation of supportive care
- Level 3: Identification of atypical features, biopsy indications, and long-term follow-up
- PSGN as the most common glomerulonephritis in children and its streptococcal latency
- Low C3 with normal C4 recovering within eight weeks and the subepithelial hump
- Supportive management and streptococcal eradication with penicillin
- Assessment and initial management of a school-aged child with smoky urine, oedema, and hypertension
- Interpretation of urinalysis with dysmorphic red cells and red cell casts, low C3, and normal C4
- Structured explanation of the mechanism, management, and prognosis of PSGN
- Recognition and supportive management of post-streptococcal glomerulonephritis
- Use of complement and streptococcal serology to confirm the diagnosis
- Identification of atypical features and indications for renal biopsy
- Recognition of PSGN as the most common glomerulonephritis in children
- Initiation of supportive care and appropriate paediatric nephrology referral
- Family communication on diagnosis, streptococcal eradication, and prognosis
- Canadian approach to PSGN diagnosis and management
- Differentiation of typical from atypical hypocomplementaemic glomerulonephritis
- Long-term renal surveillance after PSGN recovery
Overview & Definition
A previously well six-year-old who had a sore throat ten days ago and now arrives with puffy eyes, smoky brown urine, and a blood pressure of 130 over 85 has post-infectious glomerulonephritis. The disease is an immune-complex injury of the glomerulus that lands one to three weeks after a group A streptococcal throat infection or three to six weeks after a streptococcal skin infection. The injured filter leaks red cells and protein while leaking less water and salt, which is why the child looks oedematous, hypertensive, and passing cola-coloured urine all at once. [1]
Post-streptococcal glomerulonephritis (PSGN) is the single most common form of glomerulonephritis in children worldwide, and it is the prototype of the acute nephritic syndrome. The critical laboratory signature is a depressed C3 with a normal C4, because the injury is driven largely by the alternative complement pathway, and the C3 characteristically recovers to normal within six to eight weeks. That recovery is the single most useful confirmatory feature, because a C3 that stays low beyond eight weeks is no longer PSGN and points toward C3 glomerulopathy, membranoproliferative glomerulonephritis, or lupus nephritis. [5]
References12ShowHide
- [1]Rodriguez-Iturbe B, Musser JM The current state of poststreptococcal glomerulonephritis J Am Soc Nephrol, 2008.PMID 18667731
- [2]Brant Pinheiro SV, de Freitas VB, de Castro GV, Rufino Madeiro BC, de Araujo SA, et al Acute Post-Streptococcal Glomerulonephritis in Children: A Comprehensive Review Curr Med Chem, 2022.PMID 35702785
- [3]Rodriguez-Iturbe B Autoimmunity in Acute Poststreptococcal GN: A Neglected Aspect of the Disease J Am Soc Nephrol, 2021.PMID 33531351
- [4]Yoshizawa N, Yamada M, Fujino M, Oda T Nephritis-Associated Plasmin Receptor (NAPlr): An Essential Inducer of C3-Dominant Glomerular Injury and a Potential Key Diagnostic Biomarker of Infection-Related Glomerulonephritis (IRGN) Int J Mol Sci, 2022.PMID 36077377
- [5]Hisano S, Matsushita M, Fujita T, Takeshita M, Iwasaki H Activation of the lectin complement pathway in post-streptococcal acute glomerulonephritis Pathol Int, 2007.PMID 17539966
- [6]Meena J, Sinha A, Krishnasamy S, Alba AA, Aziz MA, et al AsPNA Clinical Practice Guidelines for the management of infection-related glomerulonephritis Pediatr Nephrol, 2026.PMID 41627401
- [7]Blyth CC, Robertson PW, Rosenberg AR Post-streptococcal glomerulonephritis in Sydney: a 16-year retrospective review J Paediatr Child Health, 2007.PMID 17535174
- [8]Utari IALA, Adhi S, Hermawan K, Arguni E Predictive factors of progression to chronic glomerulonephritis in pediatric patients with post streptococcal acute glomerulonephritis Pediatr Neonatol, 2024.PMID 38649317
- [9]Bajracharya P, Khadgi A, Shrestha S, Silwal R, Tandukar A Acute Post-streptococcal Glomerulonephritis in a Pediatric Population: A Five-Year Retrospective Study Cureus, 2024.PMID 38618409
- [10]Glassock RJ, Alvarado A, Prosek J, Hebert C, Parikh S, et al Staphylococcus-related glomerulonephritis and poststreptococcal glomerulonephritis: why defining post is important in understanding and treating infection-related glomerulonephritis Am J Kidney Dis, 2015.PMID 25890425
- [11]Nadasdy T, Hebert LA Infection-related glomerulonephritis: understanding mechanisms Semin Nephrol, 2011.PMID 21839370
- [12]Moges TA, Dagnew SB, Yayeh YT, Wondm SA, Dagnew FN, et al Outcomes and Predictors of Acute Post-Streptococcal Glomerulonephritis in Hospitalized Children in Northwest Ethiopia: A Multicenter Retrospective Cohort Study Health Sci Rep, 2026.PMID 42382504