Calculate the serum anion gap with albumin correction. Enter sodium, chloride, bicarbonate, and albumin to identify the type of metabolic acidosis and calculate the delta-delta ratio.
Normal: 136 – 145
Normal: 98 – 106
Normal: 22 – 26
Normal: 3.5 – 5.0 (for correction)
Anion Gap (corrected)
12.0 mEq/L
Status
Normal
Normal anion gap. If metabolic acidosis is present, consider non-anion gap causes (e.g., diarrhea, RTA).
Anion Gap = Na+ - (Cl- + HCO3-) = 140 - (104 + 24) = 12.0 mEq/L
The anion gap is within the normal range. If metabolic acidosis is present with a normal anion gap, consider hyperchloremic causes such as diarrhea, renal tubular acidosis (RTA), or normal saline infusion.
The anion gap is a fundamental tool in evaluating metabolic acidosis. It helps clinicians differentiate between causes of acidosis that produce excess organic acids (high anion gap) and those caused by bicarbonate loss or chloride retention (normal anion gap). Correcting for albumin is important because albumin is the major unmeasured anion — low albumin can mask an elevated anion gap.
The anion gap is the difference between measured cations (sodium) and measured anions (chloride + bicarbonate) in the blood. It represents unmeasured anions like albumin, phosphate, and organic acids. The formula is: AG = Na⁺ − (Cl⁻ + HCO₃⁻). Normal range is 3–12 mEq/L.
Common causes are remembered by the mnemonic MUDPILES: Methanol, Uremia, Diabetic ketoacidosis, Propylene glycol, Isoniazid/Iron, Lactic acidosis, Ethylene glycol, and Salicylates. Each introduces unmeasured organic acids into the blood.
The delta-delta ratio compares the change in anion gap to the change in bicarbonate: (AG − 12) / (24 − HCO₃⁻). A ratio less than 1 suggests a concurrent non-anion gap acidosis, 1–2 suggests a pure anion gap acidosis, and greater than 2 suggests a concurrent metabolic alkalosis.
ABG Interpreter
Enter arterial blood gas values to quickly identify acid-base imbalances. Get interpretation of the primary disorder, compensation status, and oxygenation assessment.
Corrected Calcium Calculator
Calculate the corrected calcium level adjusted for albumin. Enter total serum calcium and albumin to determine the true calcium status when albumin is abnormal.