This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Fluid and electrolytes, Subject name: Medicine
. If blood gas analysis reveal pH = 7.52, pCO2=3O; pO2= 105.This will be compensated by? 
Select and explain. 
A. Compensatory respiratory acidosis, B. Compensatory respiratory alkalosis, C. Compensatory metabolic acidosis, D. Compensatory metabolic alkalosis
C: Compensatory metabolic acidosis
Answer: C: Compensatory metabolic acidosis 
Explanation: As a compensatory mechanism, metabolic acidosis leads to alveolar hyperventilation with a fall in PaCO2. Normally, PaCO2 falls by 1-1.3 mm Hg for every 1-mEq/L fall in serum HCO3- concentration, a compensatory response that can occur fairly quickly Ref Davidson 23rd edition pg 345