Chronic Kidney Disease

CKD Basics - Kidney's Slow Fade

• Progressive, irreversible decline in kidney function.
• Diagnostic criteria (must persist ≥3 months):
  • GFR < 60 $mL/min/1.73m^2$
  • OR presence of kidney damage markers.

⭐ CKD is defined by chronicity (≥3 months) of either critically low GFR or evidence of kidney damage (e.g., albuminuria, structural issues).

• Key Kidney Damage Markers:
  • Albuminuria: ACR ≥ 30 mg/g
  • Urine sediment abnormalities
  • Electrolyte/tubular disorders
  • Structural abnormalities (imaging)
  • History of kidney transplantation
• Staging (KDIGO): GFR (G1-G5) & Albuminuria (A1-A3) categories.

CKD Culprits - Usual Suspects

⭐ Diabetes Mellitus (DM) and Hypertension (HTN) are overwhelmingly the two most common causes of CKD worldwide and in India, responsible for over two-thirds of cases.

• Other Significant Causes:
  • Glomerulonephritis (GN): e.g., IgA nephropathy, FSGS.
  • Polycystic Kidney Disease (ADPKD): Inherited cystic disorder.
  • Chronic Tubulointerstitial Nephritis: From drugs (NSAIDs), infections, reflux.
  • Obstructive Uropathy: Due to BPH, stones, strictures.
  • Autoimmune Diseases: Systemic Lupus Erythematosus (SLE).

CKD Chaos - System Breakdown

• Key Progression Drivers: Vicious cycle of Glomerular hyperfiltration → Proteinuria → Tubulointerstitial inflammation & fibrosis (TGF-β mediated) → Further nephron loss. Intrarenal RAAS activation amplifies damage.
• Systemic Complications: 📌 A WET BED
  • Acidosis (Metabolic)
  • Water-Electrolyte Imbalance: ↑$K^+$, ↑$PO_4^{3-}$, ↓$Ca^{2+}$, Fluid overload
  • EPO Failure: Anemia
  • Toxin Accumulation: Uremia (encephalopathy, pericarditis, coagulopathy)
  • Bone Disease (CKD-MBD): ↓Active Vit D, ↑PTH, ↑FGF23. Target PTH 150-300 pg/mL (Stage 5D)
  • Endocrine: Insulin resistance, ↓ T4 to T3 conversion
  • Dyslipidemia: ↑Triglycerides

⭐ Anemia in CKD is primarily due to decreased erythropoietin (EPO) production by the failing kidneys.

CKD Clues - Spotting Signs

• Clinical Features:
  • Early: Often asymptomatic.
  • Progressive: Fatigue, edema, HTN.
  • Advanced (Uremia): Nausea, vomiting, pruritus, encephalopathy.
• Key Investigations:
  • eGFR: Persistent ↓ <60 ml/min/1.73m² for >3 months ($MDRD$/$CKD-EPI$).
  • Albuminuria (Urine ACR): A1 (<30mg/g), A2 (30-300mg/g), A3 (>300mg/g).
  • Renal USG: Small, echogenic kidneys (exceptions: PCKD, diabetic).
  • Labs: Anemia, ↑$K^+$, ↑$PO_4^{3-}$, ↓$Ca^{2+}$.

⭐ Urine Albumin-to-Creatinine Ratio (ACR) is a key investigation for detecting and monitoring kidney damage in CKD, and for risk stratification.

CKD Combat - Holding Line

• Goals: Slow progression, manage complications, RRT prep.
• Slow Progression:
  • BP: <130/80 mmHg.
  • RAASi: ACEi/ARB (esp. albuminuria).

    ⭐ ACE inhibitors or ARBs are recommended for most patients with CKD, especially those with albuminuria, to slow disease progression and reduce cardiovascular risk.

  • Glucose: HbA1c <7%; SGLT2i.
  • Lifestyle: ↓Protein, ↓Na, ↓K, ↓P; stop smoking.
• Manage Complications:
  • Anemia: Hb 10-11.5 g/dL (Iron, ESAs).
  • CKD-MBD: ↓PO₄, Vit D.
  • Acidosis: NaHCO₃.
• RRT Prep:
  • AV fistula (eGFR <20-25 $mL/min/1.73m^2$).

High‑Yield Points - ⚡ Biggest Takeaways

• CKD: GFR < 60 mL/min/1.73m² for > 3 months or kidney damage.
• Top causes: Diabetes Mellitus, Hypertension.
• Complications: Anemia (↓EPO), CKD-MBD (↑PO₄, ↓Ca, ↑PTH), metabolic acidosis, hyperkalemia.
• ESRD (End-Stage Renal Disease) is GFR < 15 mL/min/1.73m² (Stage G5).
• Manage by slowing progression, treating anemia (ESAs, iron) & CKD-MBD (phosphate binders, Vit D).
• Broad waxy casts in urine sediment suggest advanced CKD.