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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.
Result 1: if there is a normal anion gap acidosis, the (AG – 12) part of the equation will be close to zero, the delta ratio will be close to zero and there is no mixed acid–base disorder. Your calculations can stop here. A normal anion gap acidosis (NAGMA) has more to do with a change in [Cl −] or [HCO − 3] concentrations.
The anion gap can be increased due to relatively low levels of cations other than sodium and potassium (e.g. calcium or magnesium). An anion gap is usually considered to be high if it is over 12 mEq/L. High anion gap metabolic acidosis is typically caused by acid produced by the body. More rarely, it may be caused by ingesting methanol or ...
One difficulty in evaluation acid-base derangements is the presence of multiple pathologies. A patient may present with a metabolic acidosis process alone, but they may also have a concomitant respiratory acidosis. Winters's formula gives an expected value for the patient's P CO 2; the patient's actual (measured) P CO 2 is then compared to this ...
The serum anion gap is useful for determining whether a base deficit is caused by addition of acid or loss of bicarbonate. Base deficit with elevated anion gap indicates addition of acid (e.g., ketoacidosis). Base deficit with normal anion gap indicates loss of bicarbonate (e.g., diarrhea).
Recall that the relationship represented in a Davenport diagram is a relationship between three variables: P CO 2, bicarbonate concentration and pH.Thus, Fig. 7 can be thought of as a topographical map—that is, a two-dimensional representation of a three-dimensional surface—where each isopleth indicates a different partial pressure or “altitude.”
Urine NH 4 + is difficult to measure directly, but its excretion is usually accompanied by the anion chloride. A negative urine anion gap can be used as evidence of increased NH 4 + excretion. In a metabolic acidosis without a serum anion gap: A positive urine anion gap suggests a low urinary NH 4 + (e.g. renal tubular acidosis).
(The serum potassium concentration may be added to the calculation, but this merely changes the normal reference range for what is considered a normal anion gap) Because the concentration of serum sodium is greater than the combined concentrations of chloride and bicarbonate an 'anion gap' is noted.