What are the reasons for high anion gap?
This is referred to as a high anion gap. Acidosis with a large anion gap is usually caused by an excess of organic acids or a proportionate reduction in anion excretion. Lactic acidosis, ketoacidosis, toluene intoxication, metabolic alkalosis, respiratory alkalosis, and severe hyperphosphatemia cause a spike in the anion gap.
How to increase anion gap?
- Malnutrition
- Liver or kidney disease
- Lithium toxicity
- Severe burns
- Sepsis
- Too much calcium, potassium, or magnesium
- Multiple myeloma
What is the significance of high anion gap?
- The name of the blood test or what was measured in your blood.
- The number or measurement of your blood test result.
- The normal measurement range for that test.
- Information that indicates if your result is normal or abnormal or high or low.
What is considered high anion gap?
High anion gap metabolic acidosis is a form of metabolic acidosis characterized by a high anion gap (a medical value based on the concentrations of ions in a patient's serum). An anion gap is usually considered to be high if it is over 12 mEq/L.
Why is anion gap important in DKA?
In DKA, an elevated anion gap indicates that lactate is continuing to be produced and thus, the body has not yet been able to achieve normal insulin-glucose regulation. Closure of the anion gap is a marker utilized by ADA to indicate that DKA has resolved.
What are symptoms of low anion gap?
Symptoms may include:shortness of breath.nausea or vomiting.edema (accumulation of fluid)abnormal heartbeat.weakness.confusion.
What can cause a high anion gap?
High anion gap acidoses are most often due to ketoacidosis, lactic acidosis, chronic kidney disease, or certain toxic ingestions. Normal anion gap acidoses are most often due to gastrointestinal or renal HCO3− loss.
What does it mean when your anion gap is low?
If you really do have a low anion gap, it could mean your blood doesn't have enough of a protein called albumin. That can be a sign of conditions like: Kidney problems. Heart disease.
Should I be worried if my anion gap is low?
If the anion gap is too low, your blood isn't acidic enough. Both high and low results may be signs of a serious disorder in your body that needs attention.
How do you increase anion gap?
The consumption of bicarbonate by the unmeasured anions will increase the anion gap by lowering the serum bicarbonate level. The total numbers of anions and cations are still equal, but the gap is increased because of a lowering of a measured anion, serum bicarbonate.
What medications affect anion gap?
The most common drugs and chemicals that induce the anion gap type of acidosis are biguanides, alcohols, polyhydric sugars, salicylates, cyanide and carbon monoxide.
What are symptoms of high anion gap?
A high anion gap itself does not produce symptoms, but it may indicate an imbalance in blood acid levels, such as metabolic acidosis....SymptomsNausea.Vomiting.Rapid and shallow breathing.Fatigue.Rapid/abnormal heartbeat.Low blood pressure.Confusion.Headaches.More items...•
Can dehydration cause high anion gap?
Severe dehydration may increase both serum albumin concentration and the anion gap.
What is the normal range for anion gap blood test?
Normal results are 3 to 10 mEq/L, although the normal level may vary from lab to lab. If your results are higher, it may mean that you have metabolic acidosis. Hypoalbuminemia means you have less albumin protein than normal.
What is the most common cause of metabolic acidosis?
The most common causes of hyperchloremic metabolic acidosis are gastrointestinal bicarbonate loss, renal tubular acidosis, drugs-induced hyperkalemia, early renal failure and administration of acids.
Do you correct sodium for anion gap?
Should the corrected sodium be used for calculating the anion gap? No! The anion gap reflects the balance between positively and negatively charged electrolytes in the extracellular fluid. Glucose is electrically neutral and does not directly alter the anion gap.
Can medication cause low anion gap?
Drugs. Lithium overdose – lithium is a commonly prescribed treatment for bipolar disorder. Since lithium is a positively charged ion, it may lower the anion gap value when present in high concentrations in the body [52, 53, 54].
What happens when your body is low on electrolytes?
When your body becomes low on electrolytes, it can impair your body's functions, such as blood clotting, muscle contractions, acid balance, and fluid regulation. Your heart is a muscle, so that means electrolytes help regulate your heartbeat.
What is the most common cause of metabolic acidosis?
The most common causes of hyperchloremic metabolic acidosis are gastrointestinal bicarbonate loss, renal tubular acidosis, drugs-induced hyperkalemia, early renal failure and administration of acids.
What can you do for low albumin levels?
Treatment for hypoalbuminemia could include:Eating a well-balanced diet to address malnutrition and heart disease.Taking blood pressure medication to address kidney disease or heart failure.Taking antibiotics to treat a severe burn.Taking anti-inflammatory medicine to treat inflammation (NSAIDs).More items...•
Why is the anion gap important?
The anion gap is clinically useful in the differential diagnosis of acid-base disorders. The anion gap is due to the presence of anions that are not measured in a standard plasma analysis , such as the negative charges associated with proteins. It is calculated as
Why is it important to calculate the anion gap?
Calculating the anion gap is critical when assessing a patient's acid-base status because an elevated anion gap may alert the physician to the presence of a metabolic acidosis that might not be apparent on first glance of the arterial blood gas values.
What is the AG in chemistry?
The anion gap (AG) is a calculated term for the difference between the commonly measured cations (Na and sometimes K) and the commonly measured anions ( Cl − and HCO 3− ). Therefore, the AG represents the unmeasured anions such as lactate, acetoacetate, and albumin. The AG is usually calculated as:
What causes a decrease in the plasma anion gap?
The plasma anion gap is normally accounted for by proteins and other organic acids in the anionic form, phosphates, and sulfate. Hypoproteinemia causes a decrease in the anion gap. Normochloremic metabolic acidosis is usually associated with an increase in the anion gap. The plasma anion gap may not change in hyperchloremic metabolic acidosis. The urinary anion gap can be used to estimate the urine NH4+ concentration. The urinary anion gap, which is usually positive, may be negative in diarrheal disease. The urinary anion gap may not provide meaningful information when the urinary bicarbonate concentration in increased, or when ketone bodies appear in urine. Non-hypoproteinemic metabolic alkalosis is associated with an increase in the anion gap.
What is an anion gap?
The anion gap is elevated in processes that result in an increase in the plasma concentration of anions that are not routinely measured in conventional chemistry panels , including lactate, phosphates, sulfates, and other organic anions (such as the degradation products of commonly ingested alcohols).
What does an anion gap of 17 mean?
An anion gap of 17 or higher represents an increased anion gap, and an anion gap of 9 or lower represents a decreased anion gap. Acid-base disturbances that are characterized by an increased, normal, or decreased anion gap have little mechanistically in common.
What is AG acidosis?
An AG acidosis is caused by the addition of a nonvolatile acid to the ECF. Examples include diabetic ketoacidosis, lactic acidosis, and uremic acidosis. A non-AG acidosis commonly (but not exclusively) represents a loss of HCO 3 −. Examples include lower GI losses from diarrhea and urinary losses due to renal tubular acidosis (RTA). Therefore, when approaching a patient with an AG acidosis, one should look for the source and identity of the acid gained. By contrast, when evaluating a patient with a non-AG acidosis, one should begin by looking for the source of the HCO 3 − loss.
What Is An Anion Gap?
The human body is composed of various components present in the body which help in the proper functioning of the body. Electrolytes are one component that is used to perform essential functions in the body. Electrolytes are electrically charged minerals which help in the control of acid and bases present in the body.
Symptoms of Anion Gap
Though mild acidemia is usually asymptomatic, high anion gap acidosis can cause the following symptoms and signs:
Causes of Low Anion Gap
The low anion gap is a rare condition but can be caused due to hypoalbuminemia, monoclonal and polyclonal gammopathy, bromide intoxication, and an increase in the positively charged ions.
Causes of High Anion Gap
Your blood is more acidic than average if your anion gap value is high. It may mean you’re suffering from acidosis. Metabolic acidosis, which is caused by the overproduction or reduced excretion of acid, is the most common condition associated with an elevated serum anion difference.
Diagnosis of Anion Gap
The test does not require any special preparation which needs to be done beforehand. your healthcare provider would brief you on whether you need to fast for the test or not. Some other blood tests require fasting which might be compulsory for the patients who need to go for other blood tests too.
Treatment of Anion Gap
The goal of treatment is to reverse the underlying cause. Correction of the underlying cause is needed for the primary treatment of high anion gap metabolic acidosis. In mild to moderate acidosis, supportive measures such as intravenous fluids and respiratory support may be sufficient.
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Why is the anion gap useful?
Uses. Calculating the anion gap is clinically useful because it helps in the differential diagnosis of a number of disease states. The total number of cations (positive ions) should be equal to the total number of anions (negative ions), so that the overall electrical charge is neutral.
What is an anion gap?
The anion gap is a calculated measure. This means that it is not directly measured by a specific lab test; rather, it is computed with a formula that uses the results of several individual lab tests, each of which measures the concentration of a specific anion or cation.
How does the anion gap affect the ketoacids?
The anion gap is affected by changes in unmeasured ions. In uncontrolled diabetes, there is an increase in ketoacids due to metabolism of ketones. Raised levels of acid bind to bicarbonate to form carbon dioxide through the Henderson-Hasselbalch equation resulting in metabolic acidosis. In these conditions, bicarbonate concentrations decrease by acting as a buffer against the increased presence of acids (as a result of the underlying condition). The bicarbonate is consumed by the unmeasured cation (H+) (via its action as a buffer) resulting in a high anion gap.
What is the difference between anion gap and cation gap?
Anion Gap = Sodium - (Chloride + Bicarbonate) which is logically equivalent to: Anion Gap = (the most prevalent cation) minus (the sum of the most prevalent anions) (Bicarbonate may also be referred to as "total CO 2 " or "carbon dioxide".)
What are the cations that are measured in the anion gap?
The cations calcium (Ca 2+) and magnesium (Mg 2+) are also commonly measured, but they aren't used to calculate the anion gap. Anions that are generally considered "unmeasured" include a few normally occurring serum proteins, and some pathological proteins (e.g., paraproteins found in multiple myeloma).
How does bicarbonate decrease?
In these conditions, bicarbonate concentrations decrease by acting as a buffer against the increased presence of acids ( as a result of the underlying condition). The bicarbonate is consumed by the unmeasured cation (H+) (via its action as a buffer) resulting in a high anion gap.
Is the anion gap positive?
In normal health there are more measurable cations than measurable anions in the serum; therefore, the anion gap is usually positive.
What is an anion gap?
The anion gap is a value that’s calculated using the results of an electrolyte blood test. Electrolytes are elements and compounds that occur naturally in the body and control important physiological functions. Calcium, chloride, magnesium, and sodium, among others, are electrolytes. Electrolytes have an electrical charge — some are positive ...
What does a high anion gap mean?
However, normal ranges may vary by lab. A high anion gap value means that your blood is more acidic than normal. It may indicate that you have acidosis. Conditions that can cause acidosis (and therefore a high anion gap value) include: diabetic ketoacidosis, a condition requiring immediate medical attention.
What causes low anion gap?
There are a few more rare causes of low anion gap. These include: 1 Bromide intoxication. Bromide is present in some sedative drugs, medication for myasthenia gravis, and some herbal medications. High concentrations of bromide can lead to neurologic or dermatologic symptoms. Although negatively charged, bromide can interfere with the calculation of chloride. This affects the calculation of the anion gap and gives a falsely low anion gap result. 2 Lithium. Lithium is positively charged and is sometimes prescribed for treatment of bipolar disorder. In high concentrations, it can lower the anion gap. 3 Increase in other positively charged ions. A large increase in other positively charged ions, such as calcium and magnesium, can also lower the anion gap.
Why do you need a second anion gap test?
If your test indicates a low anion gap value, your doctor may order a second test to account for laboratory error. Because the anion gap is calculated from the results of the electrolyte panel, accurate measurement of the individual electrolytes is necessary. A published review found that out of 67,000 calculations of anion gap, ...
What test is used to diagnose polyclonal gammopathies?
Your doctor may order a blood test to assess the levels of immunoglobulins in your blood. They may also order a serum or urine protein electrophoresis test to help monitor and diagnose your condition.
What is monoclonal gammopathy?
Monoclonal and polyclonal gammopathy. This condition refers to an overabundance of proteins (immunoglobulins) in your blood. Immunoglobulins, also known as antibodies, play a critical role in your immune system. There are many types of immunoglobulins, but one type, called IgG, is positively charged.
Is a low anion gap good?
If you seek out and get the treatment that you need for the underlying cause, the outlook for having a low anion gap is good. Following the proper treatment, your anion gap value should normalize. Last medically reviewed on November 7, 2017.
What is the anion gap?
The anion gap is a mathematical test performed on laboratory electrolyte values to determine the cause of a metabolic acidosis. It is defined as the sum of serum anion concentrations subtracted from the serum cation concentrations. Specifically, by convention the cations are sodium and potassium, and the anions are bicarbonate and chloride.
What causes a high anion gap in the absence of acidosis?
Such situations would include: Gamma-globulinaemia. High serum paraprotein in myeloma.
Can Spurious sodium alter the anion gap?
Spurious sodium results can alter the anion gap (eg. in " pseudohyponatremia ") Spurious chloride results can alter the anion gap (eg. bromide and iodide can be mistaken for chloride in the laboratory) Unmeasured or uncounted cation excess can alter the anion gap (eg. lithium, calcium, magnesium)
Overview
The anion gap (AG or AGAP) is a value calculated from the results of multiple individual medical lab tests. It may be reported with the results of an electrolyte panel, which is often performed as part of a comprehensive metabolic panel.
The anion gap is the quantity difference between cations (positively charged ions) and anions (negatively charged ions) in serum, plasma, or urine. The magnitude of this difference (i.e., "gap") i…
Calculation
The anion gap is a calculated measure. It is computed with a formula that uses the results of several individual lab tests, each of which measures the concentration of a specific anion or cation.
The concentrations are expressed in units of milliequivalents/liter (mEq/L) or in millimoles/litre (mmol/L).
Uses
Calculating the anion gap is clinically useful because it helps in the differential diagnosis of a number of disease states.
The total number of cations (positive ions) should be equal to the total number of anions (negative ions), so that the overall electrical charge is neutral. However, routine tests do not measure all types of ions. The anion gap is representative of how many ions are not accounted f…
Normal value ranges
Different labs use different formulae and procedures to calculate the anion gap, so the reference range (or "normal" range) from one lab isn't directly interchangeable with the range from another. The reference range provided by the particular lab that performed the testing should always be used to interpret the results. Also, some healthy people may have values outside of the "normal" range provided by any lab.
Interpretation and causes
Anion gap can be classified as either high, normal or, in rare cases, low. Laboratory errors need to be ruled out whenever anion gap calculations lead to results that do not fit the clinical picture. Methods used to determine the concentrations of some of the ions used to calculate the anion gap may be susceptible to very specific errors. For example, if the blood sample is not processed immediately after it is collected, continued cellular metabolism by leukocytes (also known as whit…
Correcting the anion gap for the albumin concentration
The calculated value of the anion gap should always be adjusted for variations in the serum albumin concentration. For example, in cases of hypoalbuminemia the calculated value of the anion gap should be increased by 2.3 to 2.5 mEq/L per each 1 g/dL decrease in serum albumin concentration (refer to Sample calculations, below). Common conditions that reduce serum albumin in the clinical setting are hemorrhage, nephrotic syndrome, intestinal obstruction and liver
See also
• Osmol gap
• Delta ratio
External links
• Clinical Physiology of Acid-Base and Electrolyte Disorders
• Anion Gap Calculator (includes a correction for the albumin concentration)
• Metabolic acidosis by Merck
• More information about the Figge-Jabor-Kazda-Fencl equation