📋 Clinical Utility: Anion gap helps identify the cause of metabolic acidosis.
Normal Range: 8-12 mEq/L (without albumin adjustment)
Delta-Delta: Detects mixed acid-base disorders when anion gap is elevated.

👤 Patient Information (Optional)

Age

years

Sex

🧪 Serum Values *

Serum Sodium (Na⁺) *

mEq/L

Normal range: 136-145 mEq/L.

Serum Potassium (K⁺)

mEq/L

Optional. Normal range: 3.5-5.0 mEq/L.

Serum Chloride (Cl⁻) *

mEq/L

Normal range: 98-106 mEq/L.

Serum Bicarbonate (HCO₃⁻) *

mEq/L

Normal range: 22-28 mEq/L.

🧬 Albumin Adjustment (Optional)

Serum Albumin

g/dL

Albumin correction for anion gap. Normal: 3.5-5.0 g/dL.
For every 1 g/dL decrease in albumin, anion gap decreases by ~2.5 mEq/L.

🔬 Additional Labs (Optional)

Serum Lactate

mmol/L

Elevated in lactic acidosis (normal < 2 mmol/L).

Serum Ketones Elevated in diabetic ketoacidosis (DKA) and alcoholic ketoacidosis (AKA).

📖 Causes of Anion Gap Metabolic Acidosis (MUDPILES)

High Anion Gap (MUDPILES)

Methanol
Uremia
DKA (Diabetic Ketoacidosis)
Paraldehyde
Iron, INH (Isoniazid)
Lactic acidosis
Ethylene glycol
Salicylates

Normal Anion Gap (Non-AG)

GI loss (diarrhea)
Renal tubular acidosis
Acetazolamide
Pancreatic drainage
Hyperalimentation
Ureteral diversion
Spironolactone

💡 Clinical Pearl: Winter's formula for expected PaCO₂ in metabolic acidosis:
Expected PaCO₂ = 1.5 × HCO₃⁻ + 8 ± 2
If measured PaCO₂ is higher → additional respiratory acidosis.
If measured PaCO₂ is lower → additional respiratory alkalosis.

📖 Formulas:
Anion Gap (AG) = Na⁺ - (Cl⁻ + HCO₃⁻)
Albumin-Corrected AG = AG + 2.5 × (4.0 - Albumin)
Delta Gap = (Corrected AG - 12) / (24 - HCO₃⁻)
Interpretation:
• Delta Gap < 1.0: Pure AG metabolic acidosis
• Delta Gap 1.0-2.0: Mixed AG + non-AG acidosis
• Delta Gap > 2.0: AG acidosis + metabolic alkalosis

⚡ Anion Gap & Delta-Delta Calculator

📊 Anion Gap Results

📖 Causes of Anion Gap Metabolic Acidosis (MUDPILES)

High Anion Gap (MUDPILES)

Normal Anion Gap (Non-AG)