What monitoring parameter reflects improvement after lactulose therapy?

• A. Serum ammonia level
• B. Frequency of bowel movements
• C. Blood pressure
• D. Respiratory rate

Answer: (B)

The key concept is how lactulose works in hepatic encephalopathy. Lactulose acts as an osmotic laxative and acidifies the colon, which converts ammonia (NH3) to ammonium (NH4+). Ammonium is not readily absorbed, so it stays in the gut and is excreted in stool. Because of this, the drug’s effectiveness is best observed by how well it increases stool output and consistency.

So, monitoring bowel movement frequency directly reflects the drug’s action—more frequent, softer stools indicate that ammonia is being excreted more effectively and the toxin load is decreasing. Clinically, a goal is to achieve 2-3 soft stools per day, which correlates with improved mental status as symptoms of hepatic encephalopathy lessen.

Serum ammonia levels can be helpful, but they don’t always correlate with clinical improvement, so they aren’t the most reliable standalone marker. Blood pressure and respiratory rate aren’t tied to lactulose’s mechanism or its effectiveness in clearing ammonia.