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PA27.1-2 | Normal Kidney & Clinical Syndromes — Summary & Reflection
REFLECT
Think about the three-layer filtration barrier. If the charge barrier (heparan sulphate in the GBM) is selectively disrupted but the size barrier and slit diaphragm remain intact, what would the urinalysis look like — and which clinical syndrome would result? Conversely, if inflammation physically tears the capillary wall, which syndrome follows and what casts would you expect? Articulate your reasoning before moving to SDL 2.
KEY TAKEAWAYS
Normal kidney anatomy (what you must own):
- Filtration barrier = fenestrated endothelium + GBM (charge + size) + podocyte slit diaphragm (nephrin).
- Foot process effacement → nephrotic proteinuria; RBC leakage through inflamed GBM → haematuria/RBC casts.
- PCT (metabolically vulnerable), Loop of Henle (concentration gradient), DCT/collecting duct (hormone-regulated), JGA (renin source).
- Cortex = glomeruli + PCT + DCT; Medulla = loops + collecting ducts + vasa recta.
Renal syndromes (what you must classify):
| Syndrome | Hallmark |
|---|---|
| Nephritic | Haematuria, RBC casts, mild proteinuria, HTN, oliguria |
| Nephrotic | Massive proteinuria >3.5 g, hypoalbuminaemia, oedema, lipiduria |
| Asymptomatic | Incidental haematuria/proteinuria, no symptoms |
| AKI | Rapid ↑ creatinine, oliguria, reversible (days–weeks) |
| CKD | Slow ↑ creatinine, irreversible, uraemia at end stage |
| RPGN | Rapid GN → renal failure in weeks, crescents on biopsy |
| UTI | Dysuria, WBC casts (pyelonephritis), no proteinuria |
| Nephrolithiasis | Flank pain, haematuria, no casts |
Azotaemia = elevated BUN/Cr (lab). Uraemia = symptomatic toxin accumulation (clinic).
SDL 2 covers primary glomerular diseases (post-streptococcal GN, IgA nephropathy, RPGN, membranous nephropathy, FSGS) — you are now ready.