Table of ContentsView AllTable of ContentsTest MeasurementsPurposeProcedureInterpreting ResultsHigh Anion GapLow Anion Gap
Table of ContentsView All
View All
Table of Contents
Test Measurements
Purpose
Procedure
Interpreting Results
High Anion Gap
Low Anion Gap
Along with other diagnostic tests, it can help healthcare professionals provide specific treatments, especially when individuals experience a sudden illness such as altered mental status oracute kidney failure.
This article discusses the purpose of the anion gap blood test, what the results mean, and treatment options when results are abnormal.
Yoshiyoshi Hirokawa / DigitalVision / Getty Images
Understanding pH Balance in the Body
What Does the Anion Gap Blood Test Measure?
An anion gap test can help diagnose metabolic acidosis, a life-threatening condition that occurs when your blood becomes too acidic. It can also detect alkalosis, which occurs when your blood is not acidic enough. It is important to find the cause and treat it as soon as possible.
Metabolic acidosis may occur due to:
Lactic acidbuilds up following vigorous exercise (lactic acidosis), but this is not typically enough to cause changes in the body’s pH.
Normal blood contains electrically charged particles. An anion gap is a difference between the positively charged particles and the negatively charged particles, called cations (sodium Na+andpotassium K+) and anions (chloride Cl-andbicarbonate HCO3-). These charged particles contribute to a blood’s pH.
Why You May Need the Anion Gap Blood Test
Four general conditions may require the use of the anion gap test:
You might need an anion gap blood test if you experience symptoms of an electrolyte imbalance such as:
Disorders of pH Balance in the Body
What Can You Expect During an Anion Gap Test?
The anion gap blood test usually takes less than five minutes and doesn’t require any specific preparation.
During the anion gap blood test:
The anion gap blood test is relatively safe and may be done at a hospital, emergency room, or in a lab. You may have slight pain or bruising at the injection site.
The anion gap is not usually ordered as a separate test. It tends to be ordered as part of an electrolyte panel,basic metabolic panel(BMP), orcomprehensive metabolic panel(CMP).
What Are Electrolytes?Electrolytes are minerals that have a positive or negative electric charge when they are dissolved in water or body fluids, including blood. Electrolytes are found in your blood, urine, tissues, and other body fluids. Examples of electrolytes include calcium, potassium, sodium, and chloride. They are important for many bodily functions.
What Are Electrolytes?
Electrolytes are minerals that have a positive or negative electric charge when they are dissolved in water or body fluids, including blood. Electrolytes are found in your blood, urine, tissues, and other body fluids. Examples of electrolytes include calcium, potassium, sodium, and chloride. They are important for many bodily functions.
What Do the Results of an Anion Gap Blood Test Mean?
Although there are differences between laboratories and assays, the anion gap normal range has traditionally been set between 8 mEq/L to 12 mEq/L. But, there is a wide range of normal values—often 8 to 10 mEq/L—thus an increase in anion concentration can be present in the absence of an increased anion gap.
In some cases, a false normal anion gap can occur due to severe kidney disease or certain medications. A normal anion gap with a high bicarbonate level can be one indication that the result is a false normal.
A low or high anion gap blood test determines whether you have alkalosis or acidosis.
What Does It Mean When Your Anion Gap Is High?
The most common method of evaluation of metabolic acidosis involves the Henderson-Hasselbalch equation and the Lewis model interpretation of biological acidosis, which evaluates the plasma concentration of hydrogen ions.
Correcting the underlying cause of the high anion gap (metabolic acidosis) is the primary way to mitigate potential serious health consequences.
In mild to moderate acidosis, treatment may include supportive measures, such as intravenous (IV) fluids and respiratory support. Alkalization therapy may be used for individuals with severe acidosis (pH less than 7.1 and bicarbonate less than 6 mEq/L).
What Does It Mean When Your Anion Gap Is Low?
To fix a low anion gap, treatment will depend on the underlying cause. Treatment options may include:
What to Ask Your Healthcare ProviderA low or high anion gap does not necessarily mean that you have anything to worry about. The anion gap normal range varies from person to person, so make sure you ask your healthcare provider to interpret the results of the test for you.
What to Ask Your Healthcare Provider
A low or high anion gap does not necessarily mean that you have anything to worry about. The anion gap normal range varies from person to person, so make sure you ask your healthcare provider to interpret the results of the test for you.
Summary
Treatment will depend on the cause of the blood pH imbalance.
7 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.MedlinePlus.Acidosis.MedlinePlus.Alkalosis.MedlinePlus.Respiratory acidosis.Testing.com.Electrolytes and anion gap test.MedlinePlus.Fluid and electrolyte balance.Bianchetti DGAM, Amelio GS, Lava SAG, et al.D-lactic acidosis in humans: systematic literature review.Pediatr Nephrol. 2018;33(4):673-681. doi:10.1007/s00467-017-3844-8Ghauri SK, Javaeed A, Mustafa KJ, Podlasek A, Khan AS.Bicarbonate therapy for critically ill patients with metabolic acidosis: a systematic review.Cureus. 2019;11(3):e4297. doi:10.7759/cureus.4297
7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.MedlinePlus.Acidosis.MedlinePlus.Alkalosis.MedlinePlus.Respiratory acidosis.Testing.com.Electrolytes and anion gap test.MedlinePlus.Fluid and electrolyte balance.Bianchetti DGAM, Amelio GS, Lava SAG, et al.D-lactic acidosis in humans: systematic literature review.Pediatr Nephrol. 2018;33(4):673-681. doi:10.1007/s00467-017-3844-8Ghauri SK, Javaeed A, Mustafa KJ, Podlasek A, Khan AS.Bicarbonate therapy for critically ill patients with metabolic acidosis: a systematic review.Cureus. 2019;11(3):e4297. doi:10.7759/cureus.4297
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
MedlinePlus.Acidosis.MedlinePlus.Alkalosis.MedlinePlus.Respiratory acidosis.Testing.com.Electrolytes and anion gap test.MedlinePlus.Fluid and electrolyte balance.Bianchetti DGAM, Amelio GS, Lava SAG, et al.D-lactic acidosis in humans: systematic literature review.Pediatr Nephrol. 2018;33(4):673-681. doi:10.1007/s00467-017-3844-8Ghauri SK, Javaeed A, Mustafa KJ, Podlasek A, Khan AS.Bicarbonate therapy for critically ill patients with metabolic acidosis: a systematic review.Cureus. 2019;11(3):e4297. doi:10.7759/cureus.4297
MedlinePlus.Acidosis.
MedlinePlus.Alkalosis.
MedlinePlus.Respiratory acidosis.
Testing.com.Electrolytes and anion gap test.
MedlinePlus.Fluid and electrolyte balance.
Bianchetti DGAM, Amelio GS, Lava SAG, et al.D-lactic acidosis in humans: systematic literature review.Pediatr Nephrol. 2018;33(4):673-681. doi:10.1007/s00467-017-3844-8
Ghauri SK, Javaeed A, Mustafa KJ, Podlasek A, Khan AS.Bicarbonate therapy for critically ill patients with metabolic acidosis: a systematic review.Cureus. 2019;11(3):e4297. doi:10.7759/cureus.4297
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