Confusable diagnoses · PANCE / PANRE

IgA Nephropathy vs Post-Streptococcal Glomerulonephritis

Written & clinically reviewed by Ryan Busch, PA-C · Updated August 2026 · Report an error

IgA Nephropathy and Post-Streptococcal Glomerulonephritis are easy to mix up on the boards. Here's a side-by-side comparison — presentation, workup, imaging, and first-line treatment — drawn from our full outlines.

IgA Nephropathy vs Post-Streptococcal Glomerulonephritis at a glance

  • IgA Nephropathy: Most common primary glomerulonephritis; mesangial IgA deposits with synpharyngitic hematuria.
  • Post-Streptococcal Glomerulonephritis: Immune complex GN 1-3 weeks after group A strep pharyngitis or impetigo.

Try two board-style questions on IgA Nephropathy vs Post-Streptococcal Glomerulonephritis

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Question 1RenalMedium
A 19-year-old man develops cola-colored urine two days after an upper respiratory infection. BP is elevated and urinalysis shows RBC casts. Which of the following is the most likely diagnosis?
  • AFocal segmental sclerosis
  • BImmunoglobulin A nephropathy
  • CMinimal change glomerulopathy
  • DPoststreptococcal nephritis
Reveal answer & full explanation
Correct answer: B — Immunoglobulin A nephropathy
  • AFocal segmental sclerosis
  • BImmunoglobulin A nephropathy✓
  • CMinimal change glomerulopathy
  • DPoststreptococcal nephritis

Why Immunoglobulin A nephropathy is correct

  • IgA nephropathy produces synpharyngitic hematuria, gross blood within 1-3 days of a mucosal infection.
  • RBC casts and hypertension confirm a nephritic glomerular process.
  • The very short URI-to-hematuria interval is the discriminating clue.

Why the others are wrong

  • Poststreptococcal nephritis — PSGN follows pharyngitis by 1-3 weeks with low complement; the 2-day lag is the timing trap.
  • Minimal change glomerulopathy — Minimal change is nephrotic with heavy proteinuria and edema, not RBC casts.
  • Focal segmental sclerosis — FSGS is a nephrotic-range proteinuria pattern, not URI-triggered nephritic hematuria.
Question 2RenalMedium
A 6-year-old boy presents with dark, tea-colored urine, periorbital swelling, and mild hypertension. His mother reports he had an untreated sore throat about two weeks ago that has since resolved. On exam he has mild facial edema and a blood pressure at the 95th percentile. Urinalysis shows red cell casts and 2+ protein, and a throat culture is now negative. Which of the following is the most likely diagnosis?
  • APost-streptococcal glomerulonephritis
  • BRapidly progressive glomerulonephritis
  • CAlport hereditary nephritis
  • DIgA nephropathy
Reveal answer & full explanation
Correct answer: A — Post-streptococcal glomerulonephritis
  • APost-streptococcal glomerulonephritis✓
  • BRapidly progressive glomerulonephritis
  • CAlport hereditary nephritis
  • DIgA nephropathy

Why Post-streptococcal glomerulonephritis is correct

  • This child has post-streptococcal glomerulonephritis.
  • It follows a nephritogenic group A streptococcal infection after a latent period of about 1 to 2 weeks for pharyngitis (3 to 6 weeks for skin infection), reflecting the time needed to form circulating immune complexes that deposit in the glomeruli; the defining feature is nephritic urine — hematuria, red cell casts, proteinuria, edema, and hypertension — appearing after, not during, the infection, exactly as described here.

Why the others are wrong

  • IgA nephropathy — causes gross hematuria that appears synpharyngitically, within 1 to 2 days of an upper respiratory illness rather than after a 2-week lag, so the timing here argues against it.
  • Alport hereditary nephritis — presents with recurrent hematuria plus a family history of renal disease and often sensorineural hearing loss, features absent in this single post-infectious episode.
  • Rapidly progressive glomerulonephritis — produces a rapid decline in renal function with crescents on biopsy and would not spontaneously resolve after a self-limited strep infection in an otherwise well child.

The 2-week latent period after an untreated strep throat, combined with nephritic urine, is the classic profile that identifies post-streptococcal glomerulonephritis.

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Side-by-side comparison

FeatureIgA NephropathyPost-Streptococcal Glomerulonephritis
At a glanceMost common primary glomerulonephritis; mesangial IgA deposits with synpharyngitic hematuria.Immune complex GN 1-3 weeks after group A strep pharyngitis or impetigo.
Classic presentationRecurrent episodes of cola-colored urine within 24-72 hours of a URI = synpharyngitic hematuria of IgA nephropathy.; Gross hematuria within 1-3 days of URI, GI infection, or vigorous exercise (synpharyngitic); Asymptomatic microscopic hematuria (most common presentation); Flank pain during gross hematuria episodes; Edema and…Cola-colored urine + periorbital edema + hypertension in a child 1-3 weeks after sore throat or impetigo = classic PSGN.; Abrupt onset of tea-colored or cola-colored urine (gross hematuria) 1-3 weeks after pharyngitis or 3-6 weeks after impetigo; Periorbital edema, especially in the morning; Decreased urine output; Headache and malaise…
Workup / key labsDefinitive diagnosis requires kidney biopsy showing dominant or co-dominant mesangial IgA deposition on immunofluorescence with mesangial proliferation on light microscopy. Oxford MEST-C score (mesangial hypercellularity, endocapillary, segmental sclerosis, tubular atrophy, crescents) prognosticates.; Urinalysis with microscopy —…Clinical diagnosis: nephritic syndrome + recent strep infection + low C3 + positive streptococcal serology. Biopsy reserved for atypical presentations (persistent low C3 >8 weeks, severe AKI, RPGN features) and shows endocapillary proliferative GN with subepithelial 'humps' on EM and granular IgG/C3 on IF.; Urinalysis: hematuria with…
ImagingRenal ultrasound to assess size and exclude obstruction in presence of gross hematuriaRenal ultrasound usually unnecessary; normal or mildly enlarged kidneys
First-line treatmentBP control with ACEi (lisinopril, ramipril) or ARB (losartan, valsartan) — first-line; titrate to maximally tolerated dose; SGLT2 inhibitor — dapagliflozin or empagliflozin — added for proteinuria reduction and renal protection (KDIGO 2024); Target proteinuria <0.5 g/day, ideally <0.3 g/day; BP <120/80; Lifestyle: smoking cessation,…Supportive care — most cases resolve spontaneously; Sodium and fluid restriction for volume overload; Loop diuretic — furosemide — for edema and hypertension; Antihypertensives: CCB (amlodipine) or ACEi (if renal function stable); hydralazine or nicardipine for hypertensive emergency; Antibiotics (penicillin V, amoxicillin, or…

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Full outlines

IgA Nephropathy Post-Streptococcal Glomerulonephritis (PSGN) All 514 diagnoses

Educational use only. This outline is a study aid for PA students and is not medical advice or a substitute for clinical judgment. FirstPassPA is an independent study tool and is not affiliated with, endorsed by, or sponsored by NCCPA or PAEA. PANCE® and PANRE® are registered trademarks of the National Commission on Certification of Physician Assistants; End of Rotation™ is a program of the Physician Assistant Education Association.