The Anion Gap is a useful clinical calculation made in order to break down the possible causes for metabolic acidosis:
http://en.wikipedia.org/wiki/Anion_gap
Basically, you take Sodium + Potassium - Chloride - Bicarbonate.
I have several questions on the formulas used to calculate Anion Gap:
1) In practice, potassium is left out of the calculation. This confuses me since a normal potassium serum reading is in the area of 4 mmol/L. Given that the a "normal" Anion Gap is calculated at around 8 to 16 mmol/L, removing a 4 mmol/L component of the calculation does not seem like a trivial thing. Why is it okay to ignore potassium here?
2) In terms of bicarbonate, most labs test for Carbon Dioxide, Total. I read that 80 to 90% of the Carbon Dioxide is the Bicarbonate. Should we just take 85% (mid-point) of the Total CO2 value and use that as the estimate for Bicarbonate?
Any insights here are appreciated.
http://en.wikipedia.org/wiki/Anion_gap
Basically, you take Sodium + Potassium - Chloride - Bicarbonate.
I have several questions on the formulas used to calculate Anion Gap:
1) In practice, potassium is left out of the calculation. This confuses me since a normal potassium serum reading is in the area of 4 mmol/L. Given that the a "normal" Anion Gap is calculated at around 8 to 16 mmol/L, removing a 4 mmol/L component of the calculation does not seem like a trivial thing. Why is it okay to ignore potassium here?
2) In terms of bicarbonate, most labs test for Carbon Dioxide, Total. I read that 80 to 90% of the Carbon Dioxide is the Bicarbonate. Should we just take 85% (mid-point) of the Total CO2 value and use that as the estimate for Bicarbonate?
Any insights here are appreciated.
