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 difference between certain measured cations positively charged ions and the measured anions negatively charged ions. This anion gap calculator allows you to compute the ag value and delta gap for the sodium, chloride and bicarbonate values you input in the na cl and hco3 fields. Diagnosis of metabolic acidbase disorders emcrit project. This anion gap calculator uses sodium chloride and bicarbonate values to determine the ag, delta gap and ratio. The anion gap can be readily calculated from routine laboratory data, and although it has its widest application in the diagnosis of various forms of. Anion gap calculator is an app to help medical practitioner to find the anion gap, delta gap, delta ratio, and its interpretation. The anion gap is affected by changes in unmeasured ions. In anion gap calculator, we also take account the effect of albumin on the anion gap, delta gap, and delta ratio. Delta gap anion gap 12 the anion gap ag represents the concentration of all the unmeasured anions in the plasma. Alcoholic ketoacidosis is a common cause of presentation to the emergency department with high anion gap metabolic acidosis. The anion gap is calculated via the formula provided in box 592. A recent article in ajkd by vichot and rastegar discusses the use of anion gap in metabolic acidosis. The plasma anion gap may not change in hyperchloremic metabolic acidosis.
Both calculating anion gap for acidosis student doctor. This is a health tool that can prove useful when analyzing the result of certain medical tests. The anion gap ag or agap is a value calculated from the results of multiple individual medical lab tests. It has been my experience that the correct calculation of the anion gap in the face of hyperglycemia is often confusing. An anion gap blood test is a way to check the levels of acid in your blood.
However, the second equation is used more often than the first one. It generally is believed that in the absence of detectable blood ethanol, the combination of high anion gap metabolic acidosis and increased serum osmolal gap. An example would best serve to illustrate the point. High anion gap metabolic acidosis hagma following an adverse drug interaction between paracetamol and flucloxacillin introduction paracetamol is a widely used analgesic which is available in a variety of products, including over the counter products. What is the role of an anion gap value in the workup of. The serum or plasma anion gap is an entity that is calculated from the electrolytes that are obtained in the chemical laboratory. A high anion gap see the anion gap calculator may be found in clinically ill patients who present soon after acetaminophen ingestion. A nonacidotic high anion gap state such as with excess penicillin administration. The anion gap calculator evaluates states of metabolic acidosis. Clinically significant changes in unmeasured compartment ag are usually restricted to changes in unmeasured anions, since large changes in unmeasured cations are usually not compatible with life, eg hypercalcemia hypercalcemia.
Historically, the normal range of anion gap was often quoted as being higher e. Anion gap calculator apk download for android imedical apps. Assessment of metabolic acidosis and the use of albumincorrected. A complete clinical history and physical examination are critical. The serum anion gap is calculated from the difference between the measured serum cations sodium and anions chloride and bicarbonate. Sometimes the delta gap is also use to treat acidosis. Using data on 11,957 adults from the national health and nutrition examination survey 1999 to 2004, the researchers analyzed the relation between the anion gap, as a marker of kidney function, and mortality. Toxic alcohols minding the gaps emergency medicine cases. A normally high anion gap acidosis in a patient with hypoalbuminaemia may appear as a normal anion gap acidosis. Calculates the adjusted serum anion gap, corrected for the influence of coexisting hypoalbuminemia or hyperalbuminemia. Negative anion gap and elevated osmolar gap due to lithium. The anion gap is an approximate measurement of ions, that is molecules with a charge, either negative or positive.
A delta delta gradient significantly less than 0 may result from. Anion gap is an indirect measurement of changes in the unmeasured cations or anions compartments. Mar 29, 2019 use the given standard formula for anion gap. Anion gap corrected for albumin, phosphate and lactate is a. An increase in unmeasured cations and a decrease in measured cations narrow the anion gap. There was a very strong correlation and a good agreement between anion gap corrected for albumin, phosphate and lactate and strong ion gap in the general population r 2 0. The anion gap value is reported in units of milliequivalents per liter meql. Aug 25, 2014 the serum anion gap is a common tool used in clinical practice. A serum anion gap that is below the lower limits of normal is a relatively infrequent occurrence. It is affected by many variables including serum albumin and globulin concentrations. Clinical chemistry, immunology and laboratory quality control, 2014. A 65yearold man was found in a state of clouded consciousness of unknown duration. We present a case of highvolume ileostomy output causing large bicarbonate losses and resulting in a non anion gap metabolic acidosis.
A mixed high anion gap metabolic acidosis plus a normal anion gap metabolic acidosis. Adjusted aniongap calculator, corrected for albumin. Anion gap definition of anion gap by medical dictionary. Because the gap is between 8 and 12 meql, its normal. Anion gap calculator apk download latest version 1. Please define the anion gap and its utility in diagnosis and how it relates to osmolality. Sample question on calculating metabolic acidosis anion gap. Although most commonly used in the differential diagnosis of acidbase disorders, it also has been used to assess quality control in the chemical laboratory and to diagnose paraproteinemias 4,5 and intoxications with lithium, bromide, or iodide. This adjustment returns the anion gap to the familiar scale.
Recent advances have led to a new mnemonic gold mark to differentiate the various causes of anion gap metabolic acidosis. A retrospective study of 6868 sets of serum electrolytes among hospitalized patients 3, for example, revealed incidences of increased and reduced anion gap to be 37. Pdf evaluation of serum anion gap in patients with hiv. Monoclonal proteins, especially igg, represent unmeasured cations. Elevations in anion gap are associated with specific disease states and may help narrow the ruleout list for the patient with metabolic acidosis see table 592. Every one gram decrease in albumin will decrease anion gap by 2. Calcs that help predict probability of a disease diagnosis. Anion gap acidosis associated with acetaminophen annals. A decrease in unmeasured anions decreases the anion gap. Pathological causes for both decreased and increased anion gap have been identified but increased anion gap is far more common than decreased anion gap and is usually the result of metabolic acidosis. Correcting the anion gap for hypoalbuminaemia does not. An increase in anion gap may indicate lactic acidosis or renal failure. Anion gap is defined as the difference between measured cations sodium and potassium and anions chloride and bicarbonate in serum.
After initial evaluation, calculate the anion gap every 2 to 4 hours to monitor resolution of acidosis. Anion gap delta delta gradient multicalc the merck manuals. As such, for unit increase in the anion gap, the hco3 should be lowered by 1. The differential diagnosis for an elevated anion gap metabolic acidosis simply called anion gap acidosis differs from the differential diagnosis for an nonelevated anion gap metabolic acidosis simply called non anion gap acidosis. Download32 is source for anion gap shareware, freeware download anion gap, acid base disorders, acid plus the abg calculator, medcalc 3000 kidney, acidosis, etc. The delta bicarbonate is the observed total co 2 from electrolytes subtracted from 27 and is. Prospective observational study in children with shock in a. Anion gap free download as powerpoint presentation. After the diagnosis of metabolic acidosis, the calculation of the plasmatic anion gap ag evaluates the excess of unmeasured anions. This formula can be used if there is a value for potassium.
The following questions will test your knowledge on this. Engelking, in textbook of veterinary physiological chemistry third edition, 2015. The plasma anion gap is normally accounted for by proteins and other organic acids in the anionic form, phosphates, and sulfate. Anion gap is a calculation for classifying metabolic acidosis. These two are the main cations measured in the blood. The anion gap can be readily calculated from routine laboratory data, and although it has its widest application in the diagnosis of various forms of metabolic acidosis,1, 2 it may sometimes provi. Normal results generally fall between 3 and 10 meql. Sodium and potassium are positively charged and therefore called cations. The urine anion gap in context american society of. Raised levels of acid bind to bicarbonate to form carbon dioxide through the hendersonhasselbalch equation resulting in metabolic acidosis. Often the potassium is not included in the anion gap calculation, like this. Pdf clinical usefulness of the serum anion gap researchgate. Potentially, the anion gap can provide valuable insights into the causes of metabolic acidosis in companion animals.
Some of these minerals have a positive electric charge. A mixture of high anion gap metabolic acidosis plus chronic respiratory alkalosis plus hyperchloremia acidosis. This underscores the principal clinical utility of the anion gap, which is the evaluation of patients suffering disturbance of acidbase balance. The anion gap ag is an important tool in the evaluation of metabolic acidosis. This is simply the difference in the calculated anion gap not including potassium and a normal anion gap of 12.
We now have an abg analyzer to help with acidbase analysis as well. Albumin is an unmeasured anion, whose concentration can be reduced by decreased synthesis or dilution with iv fluids. It is believed that hypoalbuminaemia confounds interpretation of the anion gap ag unless corrected for serum albumin in critically ill children with shock. Determining the serum anion gap is commonly used in the differential diagnosis of metabolic acidosis. In figges study the anion gap was calculated controlling for the effects of ph. The urine anion gap is used for differential diagnosis in metabolic acidosis using measured ions in the urine. So yes, even if they dont give you the ph from the abg, if you determine the patient is acidotic and has a high anion gap, its metabolic acidosis and consider the mudpiles list of causes. Its easy to download and install to your mobile phone. The anion gap provides an estimation of the unmeasured anions in the plasma and is useful in the setting of arterial blood gas analysis. Electrolytes are electrically charged minerals that help control the balance of chemicals in your body called acids and bases. Anion gap lab test dogs vetlexicon canis from vetstream. Anion gap, anion gap corrected for albumin, base deficit and. The anion gap can be used to help identify the cause of metabolic acidosis. Anion gap clinical calculator, anion gap medical calculator.
It is indicated for the relieve of fever and pain associated with colds and flu, fever. During the first trimester, normal anion gap ranges from 10 to 20 mmoll. There are 2 formulas you can use in calculating an anion gap. Determining if a patients acidosis also has an elevated anion gap. The patient was normoglycemic, and results of urine and. Albumin is the major unmeasured anion and contributes almost the whole of the value of the anion gap.
Pdf the anion gap in the serum is useful in the interpretation of acidbase disorders and in the diagnosis of other conditions. Anion gap is the difference between the sum of cations and anions found in plasma or serum. Anion and osmolal gaps after alcohol intoxication american. Calculating the anion gap for patients with acidosis and. A normal anion gap for pregnant women is slightly different. Abnormal anion gap is a relatively common occurrence among hospitalized patients, with increased anion gap being far more common than reduced anion gap. There are usually more measurable cations than anions, and thus a normal anion gap is value is positive. In uncontrolled diabetes, there is an increase in ketoacids due to metabolism of ketones. The normal range of anion gap is from 8 and 16 meq l milliequivalents per. The anion gap, is really not a gap at all, it just represents the anions we dont. A normal value is 316, but may vary slightly depending on the technique used by the local laboratory. Correction of the anion gap for albumin in order to detect. The anion gap ag represents the concentration of all the unmeasured anions in the plasma. A low anion gap less than 8 meql was found in 304 patients 0.
Alcohols can be divided into two broad groups based on presentation, pathophysiology and management. You can discover more on the implications of the anion gap below the form. The delta anion gap is the observed anion gap 12, which is normal, and is 0. Raised anion gap suggests there is an unmeasured anion responsible for a metabolic acidosis, eg lactate, ketones, urate, acid poisoning. The serum anion gap was 1 mmoll, and the osmolar gap 12.
Non anion gap metabolic acidosis can present as a form of either acute or chronic metabolic acidosis. However, our data showed that the anion gap increased by only 0. The difference between the two, the anion gap, is a measure of the quantity of unmeasured anions in the system. There are several explanations for the discrepancy in the expected changes in the anion gap using figges equation and the values observed in this study. The 5 big lab clues to toxic alcohol poisoning are. Serum osmolality in patients with this condition can be increased, primarily because of the presence of ethanol. Clinical aspects of the anion gap acute care testing.
Higher anion gap linked to increased mortality kidney news. However, with newer electrolyte analyzers, the upper limit of normal has decreased to 1112 mm. Acidbase disturbances can result from kidney or nonkidney disorders. To compare the ability of the ag and the albumin corrected anion gap cag to detect the presence of occult tissue anions. It is the dedication of healthcare workers that will lead us through this crisis. Assume a patient who is admitted with newonset diabetes mellitus and has the following blood test results. The toxic alcohols are methanol and ethylene glycol, which can both cause a scary anion gap metabolic acidosis in the first group and ethanol and isopropyl alcohol which arent quite as scary and generally dont cause a big anion gap metabolic acidosis in the second group. However, in order to use this information to improve diagnosis and treatment, it is important to consider several other factors about the patient, sample collection and analyser performance.
About 50% of patients have an increased anion gap metabolic acidosis due to concomitant ketoacidosis andor an increases in serum lactate levels. Pyroglutamic aciduria 5oxoprolinuria is caused by a deficiency of gluthathione synthetase of 5oxoprolinase. Interpretation of results may vary depending on various factors and underlying conditions experienced by the patient. The urine anion gap in context american society of nephrology. Initial evaluation of suspected hyperglycemic hyperosmolar state hhs. Some other potential causes of a low anion gap are as follows 2, 38, 39. This disorder has been reported after the ingestion of therapeutic doses of acetaminophen and has been fatal 1. The test is based on the results of another blood test called an electrolyte panel. Hypoproteinemia causes a decrease in the anion gap. Calculating the anion gap is critical when assessing a patients acidbase status.
554 623 285 1260 629 634 1499 1043 196 329 157 1129 89 1068 402 865 1471 1332 1488 265 433 1076 1186 131 58 215 429 914 1097 204 282 43 1464 240 230 983 1289 602 314 198 883