Conditions · Nephrology and urology
Post-streptococcal glomerulonephritis !
An immune kidney inflammation that follows a strep throat or skin infection, mostly in children, causing dark urine, swelling and high blood pressure.
Updated 2026-11-01
Structures involved
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Microorganisms that cause it
In the clinical exam
Why it happens
- Mediators of inflammation: the table to know
- When leukocytes injure tissue: proteases, oxidants and NETs
- Innate and adaptive immunity: overview
- Glomerular filtration: the barrier and its determinants
- Sodium and extracellular volume regulation (with natriuretic peptides)
- Glomerulus and the filtration barrier: podocytes, mesangium, JGA
What it is
An immune-complex glomerulonephritis that appears days to weeks after an infection with nephritogenic strains of group A Streptococcus in the throat or skin. It is the classic example of acute nephritic syndrome: haematuria, oedema, hypertension and reduced urine output.
Who gets it
Mainly affects children of preschool and early school age, more often boys. It has become rare in high-income countries but remains frequent in low- and middle-income settings, including parts of Latin America, where crowding and skin infections (impetigo, infected scabies) are common.
Causes
- Preceding infection with nephritogenic strains of group A beta-haemolytic Streptococcus (Streptococcus pyogenes)
- Pharyngitis: latent period of about 1 to 2 weeks
- Skin infection (impetigo, pyoderma): latent period of about 3 weeks or more
Risk factors
- Age about 3 to 12 years
- Overcrowding and poor hygiene
- Skin infections such as impetigo and infected scabies, more frequent in warm humid climates
- Limited access to timely care for streptococcal infections
Pathophysiology
Streptococcal antigens (such as nephritis-associated plasmin receptor and SpeB) form immune complexes that deposit in the glomeruli and activate complement, mainly by the alternative pathway, so C3 falls. The inflamed, hypercellular glomeruli filter less, causing sodium and water retention (oedema, hypertension) and leak red cells, which form red cell casts.
Classification
- Subclinical: only microscopic haematuria and low C3
- Typical acute nephritic syndrome
- Severe: rapidly progressive course with crescents, or with nephrotic-range proteinuria
Symptoms and signs
- Cola- or tea-coloured urine (haematuria) appearing 1 to 3 weeks after a sore throat or skin infection
- Puffy eyelids and face, oedema of legs
- High blood pressure, sometimes with headache
- Reduced urine output (oliguria)
- Fatigue, malaise, flank or abdominal discomfort
Diagnosis
- Clinical
- Recent pharyngitis or impetigo followed after a latent period by dark urine, oedema and hypertension; examination of the throat and skin, blood pressure, weight and signs of volume overload.
- Tests
- Urinalysis with dysmorphic red cells and red cell casts and mild to moderate proteinuria; raised creatinine and urea; low C3 (and total haemolytic complement) with normal or mildly low C4, recovering within 6 to 8 weeks; evidence of recent streptococcal infection (raised antistreptolysin O after pharyngitis, anti-DNase B after skin infection, or a positive culture); electrolytes including potassium. Biopsy only in atypical cases: it shows subepithelial humps on electron microscopy and granular (starry-sky) immunofluorescence.
- Imaging
- Chest X-ray when pulmonary oedema or cardiomegaly is suspected; kidney ultrasound in atypical or severe cases.
Differential diagnosis
- IgA nephropathy (haematuria during or just after the infection, not weeks later)
- Lupus nephritis (low C3 and C4, positive antinuclear antibodies)
- Membranoproliferative glomerulonephritis or C3 glomerulopathy (low C3 that persists)
- ANCA-associated vasculitis and anti-GBM disease (rapidly progressive course)
- IgA vasculitis (Henoch–Schönlein purpura) and infective endocarditis-related glomerulonephritis
Goal of treatment
Supportive care while the inflammation resolves: control blood pressure and fluid overload, correct electrolytes, and eradicate the streptococcus to protect contacts.
Treatment
- Medical
- Antibiotics (penicillin-class, or an alternative in allergy) to clear residual streptococci; they do not change the course of the established nephritis.
- Medical
- Loop diuretics for oedema and hypertension, with other antihypertensives such as calcium channel blockers if needed; glucocorticoids are not helpful in typical cases.
- Lifestyle
- Sodium and fluid restriction during the oliguric, oedematous phase; potassium restriction if it is high.
- Follow-up
- Nursing care: blood pressure several times a day, daily weight, strict intake and output, urine colour, neurological status, and potassium and creatinine.
- Acute
- Dialysis in the rare cases with severe kidney failure, refractory fluid overload or hyperkalaemia.
Complications
- Hypertensive encephalopathy and seizures
- Pulmonary oedema and congestive heart failure from volume overload
- Acute kidney injury and hyperkalaemia
- Rapidly progressive glomerulonephritis (rare)
- Chronic kidney disease, more often in adults
Prognosis
Excellent in children: most recover fully, with diuresis and falling blood pressure within 1 to 2 weeks and C3 normal by 8 weeks; microscopic haematuria may last months. Adults and those with crescents or heavy proteinuria are more likely to keep some kidney damage.
Prevention
- Prompt diagnosis and treatment of streptococcal pharyngitis and skin infections
- Hand washing, treatment of scabies and less household crowding
- Screening and treating close contacts during outbreaks
Test yourself
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How long after strep throat versus impetigo does post-streptococcal glomerulonephritis usually appear?
About 1 to 2 weeks after pharyngitis, and about 3 weeks or more after a skin infection.
Which complement finding is typical in post-streptococcal glomerulonephritis?
Low C3 with normal C4, returning to normal within about 6 to 8 weeks.
Which urine finding points to a nephritic rather than nephrotic syndrome?
Red blood cell casts with dysmorphic red cells (haematuria), with only mild to moderate proteinuria.
Does early antibiotic treatment of a strep skin infection prevent post-streptococcal glomerulonephritis?
Not reliably; antibiotics prevent rheumatic fever after pharyngitis but are less effective at preventing PSGN. They do limit spread to contacts.
What is the main nursing priority in the acute phase?
Monitoring blood pressure, daily weight and fluid balance to detect overload and hypertensive encephalopathy.
Related conditions
- Streptococcal pharyngitis
- Rheumatic heart disease
- Nephrotic syndrome
- Acute kidney injury
- Arterial hypertension
- Heart failure
- Chronic kidney disease
- Systemic lupus erythematosus
- Hyperkalaemia
Educational information, not medical advice. For any symptom, see a health professional.
Sources: Clinical Guidelines for Post-Streptococcal Glomerulonephritis (Centers for Disease Control and Prevention (CDC), 2025); Poststreptococcal glomerulonephritis (GN): MedlinePlus Medical Encyclopedia (MedlinePlus (U.S. National Library of Medicine), 2024).
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