Calculadora de Gap Anion (AG)

The Anion Gap (AG) Calculator is a clinical tool that helps assess acid-base balance in the blood. It calculates the difference between the main measured cations (sodium) and anions (chloride and bicarbonate) in serum. The result, known as the anion gap, is used to identify the cause of metabolic disorders, such as metabolic acidosis. The calculation is simple: AG = Na − (Cl + HCO₃). Normal values range from 8 to 12 mEq/L, although some laboratories use slightly different intervals.

The anion gap reflects the presence of unmeasured anions, such as proteins (albumin), phosphates, and sulfates. An elevated AG (>12 mEq/L) suggests metabolic acidosis with an increased anion gap, common in diabetic ketoacidosis, lactic acidosis, or intoxications (methanol, ethylene glycol). A normal AG (8-12 mEq/L) with metabolic acidosis indicates bicarbonate loss, as in diarrhea or renal tubular acidosis. The calculator is useful for physicians, students, and healthcare professionals who need to quickly interpret lab results.

To use the calculator, enter sodium, chloride, and bicarbonate values in mEq/L. The result is displayed instantly. It is important to consider that serum albumin influences the AG: for each 1 g/dL of albumin below normal (4 g/dL), the expected AG decreases by about 2.5 mEq/L. Therefore, in hypoalbuminemic patients, the AG may be falsely normal. The calculator does not replace a complete medical evaluation but speeds up clinical reasoning.

Cautions when using: ensure values are in the same unit (mEq/L). The reference range may vary between laboratories. In cases of metabolic acidosis, the AG should be interpreted along with other parameters (pH, pCO₂, bicarbonate). The calculator is educational and should not be used for self-diagnosis. Always consult a healthcare professional.