What is Anion Gap?
Anion gap is the artificial measurement of ions. The measurement is an approximated one and not accurate. Ions are molecules which carry a charge with them. Positively charge carriers are called cations and those which bear a negative charge are called anions. This is used to calculate the unmeasured ions in the plasma. This method has much clinical importance. Urine anion gap is also used in clinics though the term anion gap usually refers to the ion in the plasma. Sodium, Potassium, Magnesium and Calcium are the most commonly measured ions .Anion Gap is usually represented as AG. Negatively charged proteins constitute about 10 percentage of the plasma. Proteins like albumin, sulphates and phosphates are grouped under unmeasured anions .It is being assumed that the concentration of anions will be more than that of cations. The unit of concentration is millimoles/litre.
In a person with normal health the anion gap is usually considered to be positive. The value tends to change when there is a deviation from the normalcy. An increased anion gap can result from excess production of acid in the body or when acids are not removed in the proper manner. A rise in acid level causes increased respiratory rate, low blood pressure and poor appetite. High anion gap is an indication of reduced level of high alkaline minerals. Overproduction of ketoacid and lactic acid in the body can also account for the high anion gap. Hypoalbuminea, Lithium toxicity, hypothyroidism and any kidney associated disease can be the cause for low anion gap. A Sodium and Potassium pump functions in the body to maintain the internal and external electrical potential. Anion gap is analyzed with modern analyzers which makes use of ion selective electrodes instead of the traditional ones. Anion gap is of much clinical significance as it can predict the intensity of acidosis and the effectiveness of the treatment in a patient.