Anion Gap

Definition

• It is the sum of unmeasured anions in the serum (phosphates, sulfates, ketons, proteins,organic acids) determined by subtracting the sum of measured anions: (Na + K) - (HCO3 + Cl)

Test Sample Type

• Serum

Normal Values

• 10-15 mEq/L or 10-15 µmol/L

Purpose of the Test

• To distinguish the causes of metabolic acidosis

Abnormal in

• Severe Peripheral Vascular Disease
• Residual valve leaflets in the venous bypass graft
• Bypass graft torsion or stenosis
• Arterial thrombus or embolus
• Platelet thrombus
• Incompetent venous valve leaflets

Increase in

• Hypernatremia
• Hyperosmolar Coma
• Hypocalcemia
• Hypomagnesemia
• Ketoacidosis
• Lactic acidosis
• Starvation

Decrease in

• Hypercalcemia
• Hypermagnesemia
• Hypoalbuminemia
• Hyponatremia
• Multiple myeloma

Interfering Factor

• Dehydration
• Ingestion of licorice