How do you calculate the anion gap?

The anion gap is a useful calculation in clinical medicine, particularly when evaluating metabolic acidosis. It helps to differentiate types of metabolic acidosis by providing insight into the unmeasured anions in the plasma.

The correct formula for calculating the anion gap is (Sodium + Potassium) - (Bicarbonate + Chloride). This formula incorporates the major cations and anions in the blood to determine the gap.

In this case, sodium (Na) and potassium (K) are the primary cations, while bicarbonate (Bicarb) and chloride (Cl) represent the primary anions. By subtracting the sum of the bicarbonate and chloride from the sum of sodium and potassium, you can assess whether the measured ions align with the expected balance in normal physiological conditions. An increased anion gap often indicates the presence of additional unmeasured anions, such as lactate or ketoacids, which can occur in conditions like diabetic ketoacidosis or renal failure.

Understanding the components of the anion gap calculation is crucial for recognizing various pathological conditions, hence making this option the most appropriate choice.