1. What is the Anion Gap?

The anion gap is a calculated value used to assess acid-base disorders, particularly metabolic acidosis. It represents the difference between measured cations (positively charged ions) and measured anions (negatively charged ions) in serum.

2. How Does the Calculator Work?

The calculator uses the standard anion gap equation:

Where:

• \( \text{Na}^+ \) — Sodium concentration (mmol/L)
• \( \text{Cl}^- \) — Chloride concentration (mmol/L)
• \( \text{HCO}_3^- \) — Bicarbonate concentration (mmol/L)

Explanation: The equation calculates the unmeasured anions in plasma by subtracting the measured anions from the major measured cation (sodium).

3. Clinical Significance

Details: Normal anion gap is typically 8-12 mmol/L. Elevated anion gap suggests metabolic acidosis from unmeasured anions (e.g., lactate, ketones, toxins). Low anion gap may indicate hypoalbuminemia or other conditions.

4. Using the Calculator

Tips: Enter sodium, chloride, and bicarbonate values in mmol/L. All values must be positive numbers. The calculator will compute the anion gap automatically.

5. Frequently Asked Questions (FAQ)

Q1: What is a normal anion gap range?
A: The normal range is typically 8-12 mmol/L, though this may vary slightly between laboratories.

Q2: What causes high anion gap metabolic acidosis?
A: Common causes include lactic acidosis, ketoacidosis (diabetic, alcoholic, starvation), renal failure, and toxin ingestion (methanol, ethylene glycol, salicylates).

Q3: What causes low anion gap?
A: Low anion gap may occur with hypoalbuminemia, hypercalcemia, hypermagnesemia, lithium intoxication, or multiple myeloma.

Q4: Does the anion gap need correction for albumin?
A: Yes, the anion gap should be adjusted for albumin level (corrected AG = measured AG + 2.5 × [normal albumin - observed albumin]).

Q5: What other calculations are useful with anion gap?
A: Delta ratio (ΔAG/ΔHCO3-) and delta gap can help distinguish mixed acid-base disorders.