The anion gap (AG) is the difference between measured cations and anions in the blood. It represents unmeasured anions in the serum and is a valuable tool for diagnosing metabolic acidosis and identifying its underlying cause.
Anion Gap = Na+ - (Cl- + HCO3-)
Normal Range: 8-12 mEq/L
Some laboratories include potassium in the calculation, which yields a normal range of 10-20 mEq/L.
Albumin is a major unmeasured anion. In hypoalbuminemia, the AG may be falsely low:
Corrected AG = AG + 2.5 x (4.0 - albumin in g/dL)
Remember the mnemonic MUDPILES:
Remember the mnemonic HARDUPS:
An AG less than 3 mEq/L may indicate:
The delta-delta ratio helps identify mixed acid-base disorders:
Delta Ratio = (AG - 12) / (24 - HCO3-)
This calculator is provided for educational and informational purposes only. It should not be used as a substitute for clinical judgment or professional medical advice. Interpretation of anion gap results requires consideration of the complete clinical picture, including patient history, physical examination, and other laboratory values. Always consult with a qualified healthcare provider for medical decisions.