Overview
This lecture distinguishes nephritic and nephrotic syndromes, covering their definitions, main symptoms, pathophysiology, and the key diseases for each, with high-yield associations and buzzwords relevant for board exams.
Nephritic vs. Nephrotic Syndromes
- Both are glomerular diseases distinguished by degree of proteinuria.
- Nephrotic syndrome: >3.5g protein/day in urine; nephritic syndrome: <3.5g protein/day.
- Mixed syndromes can exist with overlapping features.
- Nephrotic: heavy proteinuria, hypoalbuminemia, hyperlipidemia, hypogammaglobulinemia, hypercoagulability.
- Nephritic: hematuria, hypertension, edema, oliguria, azotemia, acanthocytes (RBCs with spiky projections).
Nephrotic Syndromes (Key Diseases)
- Focal Segmental Glomerulosclerosis (FSGS): Most common in African Americans, Hispanics, sickle cell, HIV; effacement of foot podocytes; hyalinosis.
- Minimal Change Disease: Most common in children; often post-infection/vaccine; fusion/effacement of foot processes; normal glomeruli; negative immunofluorescence.
- Membranous Nephropathy: Associated with hepatitis B/C, lupus, NSAIDs; spike and dome appearance; thickened capillary walls; anti-PLA2R antibodies (primary).
- Diabetic Glomerulonephropathy: Most common cause of ESRD; Kimmelstiel-Wilson nodules; non-enzymatic glycosylation; microalbuminuria.
- Amyloidosis: Associated with chronic disease, TB, multiple myeloma; apple-green birefringence under polarized light; AA/AL proteins.
Nephritic Syndromes (Key Diseases)
- Post-Streptococcal GN: Children; 2–4 weeks after strep infection; type 3 hypersensitivity; decreased C3, positive ASO; lumpy-bumpy/starry sky appearance, subepithelial humps.
- Rapidly Progressive GN (RPGN): Crescents in Bowman’s space; subdivided by immunofluorescence:
- Goodpasture’s: Linear IgG, anti-GBM/anti-alveolar; hematuria/hemoptysis.
- Granulomatosis with Polyangiitis (Wegener’s): PR3-ANCA (c-ANCA), renal, lung, nasal symptoms; paucity of staining.
- Microscopic Polyangiitis: p-ANCA; renal/pulmonary; no granulomas or nasal symptoms; paucity of staining.
- Diffuse Proliferative GN: Lupus-associated; wire-loop lesions; granular IF.
- IgA Nephropathy (Berger): Follows GI/resp infection; mesangial IgA deposition; asymptomatic hematuria.
- Alport Syndrome: Defective type IV collagen; hearing loss, ocular problems, glomerulonephritis; basket-weave GBM appearance.
- Membranoproliferative GN (MPGN): Associated with hep B/C, IV drug use; tram-track GBM; type 1 (immune-mediated), type 2 (complement-mediated, dense deposit).
Key Terms & Definitions
- Proteinuria — Excess protein in urine, key in nephrotic syndrome.
- Hematuria — Blood in urine, typical in nephritic syndrome.
- Hypoalbuminemia — Low blood albumin due to urinary loss.
- Hyperlipidemia — Elevated blood lipids, seen in nephrotic syndrome.
- Crescent formation — Proliferation of cells in Bowman’s space, hallmark of RPGN.
- Tram-track appearance — Double-contour GBM, pathognomonic for MPGN.
Action Items / Next Steps
- Review tables summarizing nephrotic vs. nephritic syndromes and their associations.
- Memorize key disease associations, buzzwords, and high-yield images.
- Practice differentiating disease entities based on clinical vignettes and laboratory patterns.