KDIGO AKI Criteria & CKD-EPI 2021 Two-Dimensional Risk Stratification
Diagnostic Cascade: Select the clinical trajectory. The engine applies strict KDIGO criteria for Acute Kidney Injury (AKI) or the modern race-free CKD-EPI 2021 equation combined with Albuminuria for Chronic Kidney Disease (CKD) staging, while providing legacy Cockcroft-Gault clearances for drug dosing.
Historically, CKD was staged only by eGFR. Modern nephrology requires a two-dimensional approach (G-Stage + A-Stage). The "Why": Albuminuria indicates active glomerular endothelial damage and podocyte effacement. A patient with a perfectly normal eGFR of 90 (G1) but massive macroalbuminuria (A3) is at a significantly higher risk for rapid progression to End-Stage Renal Disease (ESRD) and sudden cardiovascular death than a patient with an eGFR of 50 (G3a) but no albuminuria (A1).
2. KDIGO Prognostic Risk Heatmap
eGFR Category (G-Stage)
A1 (< 30 mg/g or mg/24h)
A2 (30-300 mg/g or mg/24h)
A3 (> 300 mg/g or mg/24h)
G1 (≥ 90)
Low Risk
Moderate Risk
High Risk
G2 (60-89)
Low Risk
Moderate Risk
High Risk
G3a (45-59)
Moderate Risk
High Risk
Very High Risk
G3b (30-44)
High Risk
Very High Risk
Very High Risk
G4 (15-29)
Very High Risk
Very High Risk
Very High Risk
G5 (< 15)
Very High Risk
Very High Risk
Very High Risk
3. Illness Scripts: True AKI vs. Pseudo-AKI
True Acute Kidney Injury (AKI) Pathophysiology: Actual decline in Glomerular Filtration Rate (GFR) due to pre-renal (hypovolaemia), intrinsic (ATN, nephrotoxins), or post-renal (obstruction) causes. Clinical Markers: Rising Serum Creatinine accompanied by rising BUN, electrolyte derangements (hyperkalaemia), and usually altered urine output. Diagnostic Step: Evaluate Urinary Indices (FeNa, FeUrea) to differentiate pre-renal from intrinsic.
Pseudo-AKI (Creatinine Secretion Blockade) Pathophysiology: Serum creatinine rises because specific drugs block its tubular secretion via the OCT2/MATE1 transporters in the proximal tubule. Actual GFR remains completely normal. Culprit Medications: Trimethoprim (in Cotrimoxazole), Cimetidine, Fenofibrate, Cobicistat. Clinical Markers: Isolated rise in Creatinine (usually max 0.3 - 0.5 mg/dL bump). BUN remains normal. No electrolyte derangements. Resolves entirely upon drug cessation. [CLINICAL PITFALL]: Do not stop beneficial therapy or reflexively order dialysis for isolated Pseudo-AKI.
4. Indian Clinical Context: The Nephrotoxin Reality
Practice Pearl: In Indian clinical settings, a massive proportion of unexplained acute-on-chronic renal failure is driven by unrestricted over-the-counter (OTC) NSAID abuse (e.g., Diclofenac, Aceclofenac) and unregulated alternative medicines/Ayurvedic *Bhasmas* containing heavy metals. Always take a meticulous drug history. NSAIDs constrict the afferent arteriole, obliterating renal perfusion in vulnerable patients.
5. Pharmacokinetics: The Cockcroft-Gault Discrepancy
The Legacy Formula: The Cockcroft-Gault (CG) equation was developed in 1973 before standardised creatinine assays existed. Because it heavily relies on raw body weight in its numerator, it massively overestimates GFR in obese and fluid-overloaded patients.
Why Do We Still Use It? KDIGO strictly recommends CKD-EPI for *staging* disease. However, the FDA and legacy pharmaceutical manufacturers calibrated original drug dosing labels (like Vancomycin or Digoxin) using the CG formula. Therefore, CG must be referenced as a secondary output specifically for pharmacokinetic dose adjustments to prevent toxicity.
