Which treatment is used to reduce ammonia levels in hepatic encephalopathy?

• A. Antibiotics
• B. Diuretics
• C. Vitamin K
• D. Lactulose

Answer: (D)

Hepatic encephalopathy is driven by ammonia building up from gut bacteria and entering the bloodstream, so treatment focuses on lowering ammonia levels and preventing its absorption. Lactulose does this directly: in the colon it is metabolized to acids that lower the colonic pH, which shifts ammonia (NH3) to ammonium (NH4+). Ammonium is trapped in the gut and excreted in stool, reducing the amount that can cross into the blood. The laxative effect of lactulose also speeds stool passage, decreasing the time gut bacteria have to produce ammonia and further lowering absorption. Sometimes an antibiotic like rifaximin is added to reduce the population of ammonia-producing bacteria, but lactulose is the primary therapy used to reduce ammonia levels. Antibiotics can help, but they’re typically used as an adjunct, while diuretics and vitamin K don’t address ammonia directly.