Question

Which of the following describes the correct meaning of anion gap = 13 mEq/L? a, There is a 13 mEq/L gap between all the physiologically active cations and the physiologically active anions in the body. b, There are 13 mEq/L more cations than anions tested in the plasma sample. c,13 mEq/L represent the unmeasured anions bridging the gap between the major measured cations and major measured anions. d, There are 13 mEq/L more anions than cations in the tested plasma sample. please explain ?

Answer 1

The anion gap is the difference between the measured cations (positively charged ions) and the measured anions (negatively charged ions) in plasma or serum.

The anion gap is generally calculated by subtracting the plasma concentrations of chloride and bicarbonate (anions) from the concentrations of sodium and potassium (cations):- Here

Anion Gap = ([Na+] + [K+]) - ([Cl-] + [HCO3-]) = 13 mEq/L

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 for by the lab measurements used in the calculation. These "unmeasured" ions are mostly anions, which is why the value is called the "anion gap".

Example: The anion gap is affected by changes in unmeasured ions. A high anion gap indicates acidosis. In uncontrolled diabetes, there is an increase in ketoacids due to metabolism of ketones. Ketoacids are unmeasured anions, so there is a resulting increase in the anion gap. 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.

So the answer is c,13 mEq/L represent the unmeasured anions bridging the gap between the major measured cations and major measured anions.