Primary glomerular diseases

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Nephrotic vs. Nephritic - Syndrome Showdown

FeatureNephrOtic SyndromeNephrItic Syndrome
PathophysiologyPodocyte damage → ↑ protein leakageInflammation → glomerular damage
ProteinuriaMassive: >3.5 g/dayMild-moderate: <3.5 g/day
UrineFrothy urine, oval fat bodiesHematuria, RBC casts (cola-colored)
Key SignsPitting edema, ascites, hyperlipidemiaHypertension, oliguria, azotemia
Mnemonic📌 NOPHROTIC: Protein, Oedema📌 PHAROH: Proteinuria, Hematuria, Azotemia, RBC casts, Oliguria, Hypertension

RBC casts are pathognomonic for glomerulonephritis, a hallmark of nephritic syndrome. They indicate glomerular bleeding.

Primary Nephrotic Diseases - Leaky Filters Club

  • Pathophysiology: Podocyte damage → ↑ glomerular permeability → massive proteinuria (>3.5 g/day), hypoalbuminemia, edema, hyperlipidemia.

  • Minimal Change Disease (MCD)

    • Most common in children.
    • Triggers: Idiopathic, NSAIDs, viral URI.
    • Biopsy: Normal on light microscopy; EM shows effacement of podocyte foot processes.
    • Treatment: Excellent response to corticosteroids.
  • Focal Segmental Glomerulosclerosis (FSGS)

    • Most common cause in adults (esp. African American, Hispanic).
    • Associations: HIV, heroin use, sickle cell disease, obesity.
    • Biopsy: Sclerosis in parts (focal) of some (segmental) glomeruli.
  • Membranous Nephropathy

    • 📌 Membranous: Malignancy (solid tumors), Medications (NSAIDs), anti-PLA2R Abs.
    • Biopsy: LM shows thickened glomerular basement membrane. IF shows granular deposits.

Primary (Idiopathic) Membranous Nephropathy is most commonly associated with circulating antibodies to the phospholipase A2 receptor (PLA2R) on podocytes.

EM of podocyte effacement and spike and dome appearance

Primary Nephritic Diseases - Inflamed Filters Fight

  • Post-Streptococcal Glomerulonephritis (PSGN):
    • 2-4 weeks post-Group A Strep (pharyngitis/impetigo).
    • LM: Hypercellular glomeruli. IF: Granular "lumpy-bumpy" IgG, C3. EM: Subepithelial humps.
    • Presents with edema, hematuria, HTN. Low serum C3.
  • IgA Nephropathy (Berger Disease):
    • Most common primary GN worldwide. 📌 Berger's = Bloody urine after Bug (URI/GI).
    • LM/IF: Mesangial IgA deposits & proliferation.
  • Rapidly Progressive Glomerulonephritis (RPGN):
    • Clinical syndrome: rapid loss of renal function.
    • Histo: Crescent formation in Bowman's space.

⭐ Henoch-Schönlein purpura (HSP) is a systemic form of IgA nephropathy, presenting with a classic tetrad of palpable purpura, arthritis, abdominal pain, and renal disease.

Electron micrograph of glomerulus with mesangial expansion

Diagnostic Approach - Glomerular Roadmap

  • Initial Clues: Urinalysis (hematuria, proteinuria) & urine microscopy (casts).
  • Key Branching Point: Quantify proteinuria to distinguish syndromes.
    • Nephritic: < 3.5 g/day, RBC casts, HTN, azotemia.
    • Nephrotic: > 3.5 g/day, fatty casts, severe edema, HLD, hypoalbuminemia.
  • Etiology Search: Serologies (Complements, ANA, ANCA, anti-GBM, ASO).
  • Gold Standard: Kidney Biopsy (Light, Immunofluorescence, & Electron Microscopy).

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⭐ RBC casts are pathognomonic for glomerulonephritis. In nephrotic syndrome, severe hypoalbuminemia (e.g., < 2.5 g/dL) leads to ↓ plasma oncotic pressure, causing massive edema.

High‑Yield Points - ⚡ Biggest Takeaways

  • Minimal Change Disease: Top nephrotic cause in children; podocyte effacement with dramatic steroid response.
  • FSGS: Leading nephrotic cause in African Americans; linked to HIV, sickle cell, and heroin use.
  • Membranous Nephropathy: Common in adults; defined by anti-PLA2R antibodies and "spike-and-dome" appearance.
  • IgA Nephropathy: Most common GN worldwide; presents with gross hematuria concurrently with a URI.
  • Post-streptococcal GN: Occurs 1-3 weeks post-infection; marked by low C3 and subepithelial "humps".

Practice Questions: Primary glomerular diseases

Test your understanding with these related questions

A 41-year-old man presents at an office for a regular health check-up. He has no complaints. He has no history of significant illnesses. He currently takes omeprazole for gastroesophageal reflux disease. He occasionally smokes cigarettes and drinks alcohol. The family history is unremarkable. The vital signs include: blood pressure 133/67 mm Hg, pulse 67/min, respiratory rate 15/min, and temperature 36.7°C (98.0°F). The physical examination was within normal limits. A complete blood count reveals normal values. A urinalysis was ordered which shows the following: pH 6.7 Color light yellow RBC none WBC none Protein absent Cast hyaline casts Glucose absent Crystal none Ketone absent Nitrite absent Which of the following is the likely etiology for hyaline casts in this patient?

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Flashcards: Primary glomerular diseases

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Which type of nephrotic syndrome is commonly seen secondary to solid tumors? _____

TAP TO REVEAL ANSWER

Which type of nephrotic syndrome is commonly seen secondary to solid tumors? _____

Membranous nephropathy

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