Important Points in Renal System

Urinary Findings & Associated Diseases

S/No.	Disease	Key Finding in Urine
1	Acute Pyelonephritis	WBC casts in urine
2	Acute Cystitis	WBCs in urine
3	Glomerulonephritis	RBC casts in urine
4	Bladder Carcinoma	RBCs in urine
5	Chronic End-stage Renal Disease	Waxy casts

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Glomerular Diseases & Key Findings

S/No.	Disease	Key Finding
1	IgA Nephropathy (Berger’s Disease)	Cola or tea-colored urine
2	Type-1 MPGN, SLE Nephritis	Mesangial electron-dense deposit
3	Type-2 MPGN	Intramembranous deposit
4	Goodpasture Syndrome	Anti-GBM antibody
5	Post-streptococcal GN	Sub-epithelial humps
6	Membranous Glomerulopathy	Sub-epithelial deposit
7	Minimal Change Disease	Effacement of foot processes of podocytes
8	Goodpasture Syndrome	Hemoptysis + Hematuria
9	Alport Syndrome	Deafness + Hematuria
10	Wegener’s Granulomatosis	Sinusitis + Hemoptysis + Hematuria

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High-Yield Nephrology Points

• IgA Nephropathy (Berger’s Disease) → Most common cause of nephritic syndrome

• Focal Segmental Glomerulosclerosis (FSGS) → Most common cause of nephrotic syndrome in adults

• Minimal Change Disease → Most common cause of nephrotic syndrome in children

General High-Yield Nephrology Facts

• IgA Nephropathy (Berger’s disease) → Most common cause of nephritic syndrome worldwide.
• Post-streptococcal glomerulonephritis → Most common cause of nephritic syndrome in children.
• Minimal Change Disease (MCD) → Most common cause of nephrotic syndrome in children; responds dramatically to steroids.
• Focal Segmental Glomerulosclerosis (FSGS) → Most common cause of nephrotic syndrome in adults (especially in African descent and HIV patients).
• Membranous Nephropathy → Most common cause of nephrotic syndrome in white adults; associated with HBV, HCV, SLE, malignancy.
• Diabetic Nephropathy → Most common cause of end-stage renal disease in developed countries.
• Amyloidosis → Nephrotic-range proteinuria; Congo red positive, apple-green birefringence.

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Characteristic Urinary Cast Associations

• RBC casts → Glomerulonephritis, vasculitis.
• WBC casts → Pyelonephritis, interstitial nephritis.
• Granular (muddy brown) casts → Acute tubular necrosis (ATN).
• Waxy casts → Chronic kidney disease, ESRD.
• Fatty casts (Maltese cross appearance) → Nephrotic syndrome.
• Hyaline casts → Nonspecific; can be normal in dehydration or exercise.

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Classic Triads & Syndromic Associations

• Goodpasture Syndrome → Hemoptysis + Hematuria + Anti-GBM antibodies.
• Alport Syndrome → Hematuria + Sensorineural deafness + Ocular defects; “basket-weave” GBM on EM.
• Wegener’s (Granulomatosis with polyangiitis) → Sinusitis + Hemoptysis + Hematuria; c-ANCA positive.
• Microscopic Polyangiitis → Hemoptysis + Hematuria; p-ANCA positive; no granulomas.

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Special Histopathology & EM Findings

• Minimal Change Disease → Effacement of podocyte foot processes.
• FSGS → Segmental sclerosis & hyalinosis.
• Membranous Nephropathy → Spike-and-dome appearance on silver stain; subepithelial deposits.
• Post-streptococcal GN → Lumpy-bumpy (granular) deposits; subepithelial humps.
• MPGN Type 1 → Subendothelial deposits; tram-track GBM splitting.
• MPGN Type 2 (Dense Deposit Disease) → Intramembranous dense deposits.
• Lupus Nephritis → Wire-loop capillaries; full-house immunofluorescence (IgG, IgA, IgM, C3, C1q).

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Other Must-Know Nephrology Facts

• Hyperkalemia in CKD is often worsened by ACE inhibitors, ARBs, potassium-sparing diuretics, and NSAIDs.
• Nephrotic syndrome → Hypercoagulable state due to loss of antithrombin III in urine.
• Nephritic syndrome → Usually due to immune-mediated GBM damage with inflammation.
• RPGN (Crescentic GN) → Rapidly progressive renal failure; crescents on light microscopy; poor prognosis without aggressive therapy.
• ADPKD → Associated with berry aneurysms, hepatic cysts, and mitral valve prolapse.
• ARPKD → Associated with Potter sequence and congenital hepatic fibrosis.