Define anion gap and its practical use in evaluating metabolic acidosis.

Define anion gap and its practical use in evaluating metabolic acidosis.

• A. Anion gap = Cl - (Na + HCO3-); normal ~-8 to -12; elevated AG suggests bicarbonate excess.
• B. Anion gap = Na - (Cl + HCO3-); normal ~8-12; elevated AG suggests unmeasured anions.
• C. Anion gap = Na + K - (Cl + HCO3-); normal ~20-24; elevated AG indicates electrolyte imbalance.
• D. Anion gap = Ca - (PO4 + Mg); normal ~2-4; elevated AG indicates calcium imbalance.

Answer: (B)