The Anion Gap Calculator computes the serum anion gap from sodium, bicarbonate, and chloride using AG = Na⁺ − (HCO₃⁻ + Cl⁻). The app's own reference card cites a normal anion gap of 10–12 mEq/L, while noting many labs use a wider 8–16 mEq/L range. It then bands the result into low, normal, mild-high, and high categories, each linked to a differential diagnosis to guide the work-up of metabolic acidosis.
It calculates AG = Na⁺ − (HCO₃⁻ + Cl⁻) from serum sodium, bicarbonate, and chloride, per the app's result card.
The app's reference card lists a normal anion gap of 10–12 mEq/L, while noting many labs use a wider 8–16 mEq/L range; its own interpretation bands treat 8–12 mEq/L as normal.
The app flags anion gaps above 20 mEq/L as a significant high-anion-gap metabolic acidosis and lists the MUDPILES mnemonic (methanol, uraemia, DKA/ketoacidosis, paracetamol/propylene glycol, iron/INH, lactic acidosis, ethylene glycol, salicylates) as the differential.
The tool lists hypoalbuminaemia as the most common cause, along with bromism, lithium toxicity, hypercalcaemia, and multiple myeloma, and recommends correcting the AG for albumin when albumin is low.
The app states its interpretation bands are drawn from the Harriet Lane Handbook (23rd edition) and Nelson Textbook of Pediatrics (21st edition).