Evaluates metabolic acidosis
Total Score
Abnormally low Anion Gap (< 3). Check for lab errors, hypoalbuminemia (correct AG by +2.5 per 1 g/dL below 4.0), or paraproteinemia.
Disclaimer: The clinical scoring and algorithms on this platform are intended strictly for professional informational purposes. They do not constitute a definitive medical diagnosis, treatment, or clinical decision. The final judgment and responsibility lie with the treating physician.
Yasal Uyarı: Bu platformdaki klinik skorlamalar ve algoritmalar yalnızca sağlık profesyonellerini bilgilendirme amaçlıdır. Herhangi bir kesin tıbbi teşhis, tedavi veya klinik karar yerine geçemez. Nihai karar ve sorumluluk hastayı yatak başında değerlendiren hekime aittir.
The serum Anion Gap is a fundamental calculation in evaluating acid-base disorders, particularly metabolic acidosis. It represents the unmeasured anions in the plasma (primarily negatively charged proteins like albumin, sulfates, and phosphates). An elevated anion gap indicates the presence of exogenous or endogenous pathological acids (e.g., ketones, lactate, toxic alcohols) commonly remembered by the MUDPILES mnemonic.
Albumin constitutes the bulk of the normal unmeasured anions. Therefore, in a critically ill patient with severe hypoalbuminemia, the 'baseline' anion gap is inherently lower. You must calculate the 'Corrected Anion Gap'; roughly, for every 1 g/dL drop in albumin below 4.0, add 2.5 mEq/L back to the calculated anion gap to avoid missing a hidden high-gap acidosis.
Kraut JA, Madias NE. Serum anion gap: its uses and limitations in clinical medicine. Clin J Am Soc Nephrol. 2007;2(1):162-174.
Disclaimer: The clinical scoring and algorithms on this platform are intended strictly for professional informational purposes. They do not constitute a definitive medical diagnosis, treatment, or clinical decision. The final judgment and responsibility lie with the treating physician.
Calculate the anion gap in any patient with metabolic acidosis (pH < 7.35 and HCO₃ < 22 mEq/L). It is the essential first step in the metabolic acidosis algorithm — it distinguishes high-AG acidosis (MUDPILES etiology) from normal-AG acidosis (HARDUPS etiology) and guides the subsequent diagnostic workup. Always correct the AG for albumin: add 2.5 mEq/L for every 1 g/dL the albumin is below 4.0 g/dL.
The delta-delta ratio (Δ-Δ) unmasks mixed acid-base disorders hidden behind an elevated AG. Calculate it as: (measured AG − 12) / (24 − measured HCO₃). A ratio of 1–2 indicates a pure HAGMA. A ratio < 1 means there is a concurrent normal-AG acidosis (the HCO₃ fell more than the AG rose). A ratio > 2 means there is a concurrent metabolic alkalosis (the HCO₃ fell less than expected — it was partly "rescued" by an alkalotic process). This calculation is particularly valuable in the ICU, where mixed acid-base disorders are common.
Hypoalbuminemia is the most common cause of a spuriously low anion gap and will mask a true HAGMA. In critically ill patients with albumin of 2.0 g/dL, the corrected AG is the measured AG + 5.0 mEq/L — an apparently normal AG of 9 mEq/L would be a corrected AG of 14 mEq/L, which is abnormal. Failure to albumin-correct is the leading cause of missed HAGMA in the ICU.