1. What is the Anion Gap?

The anion gap is a calculated value that represents the difference between measured cations and anions in serum. It's used to assess acid-base disorders, particularly metabolic acidosis.

2. How Does the Calculator Work?

The calculator uses the standard anion gap equation:

Where:

• \( \text{Na}^+ \) — Serum sodium concentration (mmol/L)
• \( \text{Cl}^- \) — Serum chloride concentration (mmol/L)
• \( \text{HCO}_3^- \) — Serum bicarbonate concentration (mmol/L)

Explanation: The equation calculates the unmeasured anions in serum by subtracting the measured anions (chloride and bicarbonate) from the primary measured cation (sodium).

3. Clinical Significance

Details: Normal anion gap is typically 8-16 mmol/L. An elevated gap suggests the presence of unmeasured anions (e.g., lactate, ketones, toxins) in metabolic acidosis. A low gap may indicate hypoalbuminemia or other conditions.

4. Using the Calculator

Tips: Enter serum sodium, chloride, and bicarbonate values in mmol/L. All values must be valid (greater than 0).

5. Frequently Asked Questions (FAQ)

Q1: What is a normal anion gap range?
A: The normal range is typically 8-16 mmol/L, though this may vary slightly by laboratory.

Q2: What causes an elevated anion gap?
A: Common causes include lactic acidosis, ketoacidosis, renal failure, and toxic alcohol ingestion (MUD PILES mnemonic).

Q3: Can the anion gap be too low?
A: Yes, a low anion gap may occur with hypoalbuminemia, hypercalcemia, hypermagnesemia, or multiple myeloma.

Q4: Are there alternative versions of the anion gap?
A: Some formulas include potassium (Na + K - Cl - HCO3), and albumin-corrected versions exist for patients with hypoalbuminemia.

Q5: How should results be interpreted clinically?
A: Always interpret in clinical context with other labs and patient presentation. Anion gap is just one component of acid-base assessment.