25 year old male patient presents with ingestion of antifreeze solution.His arterial blood has analysis report is as follows :
PH = 7.20
Anion gap = 15
PCO2 = 25
HCO3 = 10
most likely diagnosis is: (A) High Anion gap metabolic acidosis, (B) Normal Anion gap  metabolic acidosis, (C) Both, (D) None
Answer is C. anion gap =15 (high)
Difference in anion gap : 15-10= 5
Difference in HCO3 levels : 25-10=15

As difference in HCO3 levels is more than that of anion gap , this is a case of High anion gap metabolic acidosis + compensatory respiratory alkalosis + normal anion gap metabolic alkalosis.