Which bicarbonate abnormality is described in anorexia purging type?

• A. High bicarbonate
• B. Low bicarbonate
• C. Normal bicarbonate
• D. Variable bicarbonate

Answer: (A)

Purging through vomiting causes loss of gastric acid (HCl), which reduces hydrogen and chloride in the body and pushes the system toward alkalosis. The kidneys respond by conserving bicarbonate and reabsorbing more of it, and the volume depletion from fluid loss activates hormonal mechanisms (like aldosterone) that promote hydrogen and potassium loss in exchange for sodium, further increasing bicarbonate relative to hydrogen. The net effect is an elevated serum bicarbonate, i.e., metabolic alkalosis. This pattern is typical for anorexia nervosa with purging. The other possibilities don’t fit as well: losing acid from vomiting raises bicarbonate, not lowers it; normal or highly variable bicarbonate would not reflect the characteristic acid-base change from purging.