The anion gap (in mmol/L) = (Na+ K) - (HCO3 + Cl)
An anion gap of 7 - 17 mmol/L is normal.

An anion gap > 17 mmol/L, in the presence of acidosis suggests:

• lactic acidosis - may be secondary to shock or seizures from a number of poisons
• diabetic, alcoholic or starvation ketoacidosis
• renal failure (GFR < 10% of normal)
• infantile organic acidosis

or poisoning with one of the following toxins that alter metabolism leading to acidosis:

• Benzyl alcohol
• Beta-adrenergic agents
• Caffeine
• Carbon monoxide
• Cyanide
• Ethanol
• Ethylene glycol
• Hydrogen sulfide
• Ibuprofen
• Iron
• Isoniazid (INH)
• Lithium
• Metformin
• Methanol
• Paracetamol
• Paraldehyde
• Phenformin
• Salicylates
• Strychnine
• Sympathomimetic amines
• Toluene