Nephrology
Delta-Delta Ratio (Delta Gap)
Evaluates mixed acid-base disorders in high anion gap metabolic acidosis.
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Parameters
Delta-Delta Ratio (Delta Gap) Result
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Formula
Delta Ratio = (Anion Gap - 12) / (24 - Serum HCO₃⁻)
where Anion Gap = Na⁺ - (Cl⁻ + HCO₃⁻)Clinical Pearls
Detects occult, hidden metabolic alkalosis or non-anion gap acidosis that would otherwise be masked on a standard basic metabolic panel.
Limitations
Assumes baseline normal anion gap is 12 and baseline normal bicarbonate is 24; hypoalbuminemia lowers baseline normal anion gap (by ~2.5 mEq/L per 1 g/dL drop in albumin).