Given specific lab results, what is the calculated anion gap if sodium is 145 mmol/L, potassium 4.0 mmol/L, chloride 100 mmol/L, and bicarbonate 22 mmol/L?

To calculate the anion gap, the formula used is:

Anion Gap = (Sodium + Potassium) - (Chloride + Bicarbonate)

In this case, substituting in the provided lab values:

• Sodium = 145 mmol/L

• Potassium = 4.0 mmol/L

• Chloride = 100 mmol/L

• Bicarbonate = 22 mmol/L

First, sum the sodium and potassium:

145 + 4.0 = 149 mmol/L

Next, sum the chloride and bicarbonate:

100 + 22 = 122 mmol/L

Now, subtract the second sum from the first:

Anion Gap = 149 - 122 = 27 mmol/L

The calculated anion gap of 27 mmol/L reflects the difference between the measured cations (sodium and potassium) and the measured anions (chloride and bicarbonate). This value is particularly important in clinical settings as it helps to assess metabolic acidosis and differentiate between various types based on the presence of unmeasured anions.

This calculated value confirms that option B, 27, is the correct choice and aligns with the expected methodologies for determining anion gaps in clinical laboratories.