Anion Gap(K+) is the concentration difference between the cations, sodium and potassium, and the measured anions, chloride and bicarbonate.
Anion Gap(K+) = cNa+ + cK+ - cCl– - cHCO-3.
The systematic symbol is Anion Gap(K+). The analyzer symbol may be Anion Gap(K+).
What does Anion Gap(K+) tell you
Anion Gap(K+) is a reflection of the unmeasured anions in the plasma, e.g., proteins, organic acids, sulfates, and phosphates (although changes in plasma calcium and magnesium also affect the Anion Gap(K+)).
Anion Gap(K+) may be an aid in the differential diagnosis of metabolic acidosis. Metabolic acidosis can be classified in two groups:
- Those with an increase in Anion Gap(K+), thus implying the presence of increased amounts of organic acid.
- Those with normal Anion Gap(K+), due to loss of bicarbonate.
Anion Gap(K+) reference range (adult): 10-20 mmol/L
A. Decreased Anion Gap(K+) can be caused by:
- Decrease in plasma proteins
- Increase in unmeasured cations
B. Increased Anion Gap(K+) can be caused by:
- Renal failure
- Intoxication with: salicylate, methanol, and ethylene glycol
C. Metabolic acidosis with a normal Anion Gap(K+):
- Uremic acidosis of recent onset
- Renal tubular acidosis