Anion gap refers to the difference between the total number of cations measured in serum and the total number of anions, which can identify different types of metabolic acidosis. Usually expressed as (Na+-C1--HC03-). This is an important indicator of metabolic acidosis and can provide important clues for the diagnosis of many potentially fatal diseases. AG=(Na++K+)-(Cl--HCO3-) is generally calculated using the electrolyte content in serum. The serum K+ concentration is low and relatively constant, and the effect on AG is slight, so the above formula can be simplified to AG=Na+-(Cl-+HCO3-).

Basic Information

Specialist classification: growth and development check classification: biochemical examination

Applicable gender: whether men and women apply fasting: fasting

Tips: Before taboos: Avoid taking drugs. Normal value

The normal reference value of AG is 8-16 mol/L, with an average of 12 mmol/L. Clinically, the measured value of serum yin and cation can be used to calculate the AG value, which has certain value for the differential diagnosis of the etiology and type of metabolic acidosis.

Clinical significance

Abnormal result

Increased in metabolic acidosis, diabetic ketoacidosis, uremia and so on. Severe hypoxemia, severe infection with shock or circulatory failure, renal insufficiency leading to azotemia or uremia, alkalosis, and too little food intake caused by ketoacidosis.

Normal anion gap metabolic acidosis such as high blood chlorine metabolic acidosis.

Reduction is seen in hypoproteinemia and the like.

High results may be diseases: lactic acidosis, metabolic acidosis precautions

Contraindications before inspection: Avoid taking drugs indiscriminately.

Requirements for inspection: Keep it in a relaxed state and cooperate with the doctor.

Inspection process

Only a part of the anions (such as Cl- and) are determined in the routine test, which is called "measurable anion", which accounts for 85% of the total number of anions. The "measurable anion" is subtracted from the total number of all cations, the difference being called AG. Since Na+ accounts for 90% of the total number of cations, the total number of cations is usually replaced by Na+.

Not suitable for the crowd

Other high-risk conditions should not be done this check.

Adverse reactions and risks

Generally, this examination does not have too many adverse reactions and does not have much influence on the body.