FCPS part 1 Medicine solved mcqs with explanation Q8

Q8: Serum Gastrin levels are increased by prolonged use of:

a) H₂ Receptor blockers

b) Proton Pump Inhibitors

c) Antacids

d) Anticholinergics

Correct Answer: b

Explanation:

The most appropriate answer is Proton Pump Inhibitors (PPI) because they irreversibly inhibit H⁺ /K⁺ -ATPase in stomach parietal cells. H₂ blockers on the other hand cause a reversible block of histamine H2 receptors resulting in decreased production of H⁺. Since the PPI are irreversible blockers of the Proton pump they cause a more sustained decrease in H⁺ production. This, through positive feedback increases the secretion of Gastrin. Generally increased acid (H⁺ ions) causes decreased production of Gastrin & decreased acid (such as through PPI use) cause increase in Gastrin secretion.