Nephrotic and Nephritic Syndromes

Syndrome Overview - Defining the Duo

                   | Mild-moderate: $ < \textbf{3.5g/24h}## Syndrome Overview - Defining the Duo

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| Hematuria | Often absent/microscopic | Gross/microscopic; RBC casts | | Edema | Severe, generalized (hypOalbuminemia) | Mild, periorbital (Na⁺/water retention) | | Hypertension | Less common, may be late | Common, often abrupt (Increased BP) | | Renal Function | Often preserved initially | Often Impaired (↑ creatinine, oliguria) | | Key Features | HypOalbuminemia, hyperlipidemia, lipiduria | Immune complex deposition | | Mnemonic | 📌 PrOteinuria, HypOalbuminemia, Oedema, Hyperlipidemia | 📌 Inflammation, Immune complexes, Increased BP, Impaired renal fn. |> ⭐ Oval fat bodies (Maltese cross appearance under polarized light) are characteristic of nephrotic syndrome.

Nephrotic Syndrome - Leaky Filters Galore

Pathophysiology: Podocyte injury, loss of GBM negative charge → ↑ protein permeability.

Cardinal Features:

• Proteinuria: $ > \textbf{3.5 g/24h}$ (or $ > \textbf{50 mg/kg/day}$ children).
• Hypoalbuminemia: Serum albumin $ < \textbf{3 g/dL}$.
• Generalized Edema: Anasarca, often periorbital.
• Hyperlipidemia & Lipiduria: Oval fat bodies, fatty casts.

📌 NAPHROTIC Mnemonic: Na+ retention, Albuminuria, Proteinuria ($ > \textbf{3.5g/day}$), Hyperlipidemia, Renal vein thrombosis, Orbital edema, Thromboembolism, Infection, Coagulability.

Common Causes:

• Primary Glomerular Diseases:

  Disease	Key Biopsy Finding
  MCD	Podocyte effacement (EM)
  FSGS	Segmental sclerosis (LM)
  Membranous Neph.	Thick GBM, subepithelial spikes (EM/IF)

• Secondary Causes:
  • Diabetes Mellitus (most common in adults)
  • Amyloidosis
  • SLE (Class V)

⭐ Minimal Change Disease is the most common cause of nephrotic syndrome in children and shows diffuse effacement of podocyte foot processes on electron microscopy.

Nephritic Syndrome - Inflamed & Angry Gloms

Pathophysiology: Glomerular inflammation & immune complex deposition → glomerular injury, ↓GFR.

• Cardinal Features (📌 PHARAOH):

  • Proteinuria (mild-moderate, <3.5 g/day)
  • Hematuria (cola-colored urine, RBC casts present)
  • Azotemia (↑BUN, ↑Creatinine)
  • RBC casts (confirms glomerular hematuria)
  • Anti-Strep titres (↑ in PSGN, e.g., ASO >200 IU/mL)
  • Oliguria (<400 mL/day)
  • Hypertension (HTN)

• Common Causes:

  • Primary Glomerulonephritis (GN):

    Cause	Key Biopsy Finding
    IgA Nephropathy	Mesangial IgA deposits
    PSGN	Diffuse hypercellularity, subepithelial "humps"
    RPGN	Crescents in Bowman's space

  • Secondary: SLE, Henoch-Schönlein Purpura (HSP), Vasculitis (e.g., GPA, MPA).

⭐ PSGN: 1-3 wks (pharyngitis) or 2-6 wks (impetigo) post-infection; features subepithelial 'humps' (EM), low C3.

Key Glomerulopathies - Rogues' Gallery

⭐ IgA Nephropathy is the most common glomerulonephritis worldwide and often presents with episodic macroscopic hematuria concurrent with mucosal infections.

High‑Yield Points - ⚡ Biggest Takeaways

• Nephrotic Syndrome is defined by massive proteinuria (>3.5 g/day), hypoalbuminemia, edema, and hyperlipidemia.
• Minimal Change Disease: commonest nephrotic in children; effacement of podocyte foot processes on EM.
• Nephritic Syndrome presents with hematuria (RBC casts), oliguria, hypertension, and azotemia.
• Post-Streptococcal Glomerulonephritis (PSGN): classic nephritic, ↑ASO titers, low C3, subepithelial "humps".
• IgA Nephropathy (Berger's Disease): most common primary glomerulonephritis; recurrent hematuria often after URI.