Acid Base Calculator

This calculator relies on standard physiological formulas used in emergency medicine and nephrology. The primary metric is the Anion Gap, which measures the difference between primary measured cations and anions in the serum. It is calculated using the formula: Anion Gap = Sodium - (Bicarbonate + Chloride). Because abnormal serum albumin levels can artificially skew the anion gap, the calculator also computes a Corrected Anion Gap using the formula: Corrected Anion Gap = Anion Gap + 2.5 * (4.4 - Albumin). This adjustment ensures diagnostic accuracy in patients with hypoalbuminemia, preventing missed diagnoses of high anion gap metabolic acidosis.

Consider a patient presenting to the emergency department with the following metabolic panel and blood gas results: Sodium (Na+) = 138 mEq/L, Chloride (Cl-) = 100 mEq/L, Bicarbonate (HCO3-) = 18 mEq/L, and Serum Albumin = 2.4 g/dL. First, we calculate the standard anion gap: 138 - (18 + 100) = 20 mEq/L. Next, to account for the patient's low albumin level (normal baseline roughly 4.4 g/dL), we apply the correction formula: 20 + 2.5 * (4.4 - 2.4) = 20 + 2.5 * (2.0) = 20 + 5.0 = 25 mEq/L. The final corrected anion gap of 25 mEq/L clearly indicates a significant high anion gap metabolic acidosis requiring immediate clinical investigation.

Always verify that all laboratory values used in the calculator were drawn from the same blood sample to ensure internal consistency. Remember that electrolyte panels and arterial blood gases (ABGs) should be interpreted within the full clinical context of the patient's history, current medications, and vital signs. Lastly, always use corrected anion gap formulas when evaluating patients with chronic liver disease, malnutrition, or nephrotic syndrome where baseline albumin is abnormally low.