Which condition would specifically increase only unconjugated bilirubin?

The condition that specifically increases only unconjugated bilirubin is hemolytic anemia. In hemolytic anemia, the premature destruction of red blood cells leads to the release of hemoglobin, which is then broken down into bilirubin. This process results in an increase in unconjugated bilirubin levels because the liver's capacity to conjugate the excess bilirubin may become overwhelmed.

In this scenario, unconjugated bilirubin accumulates in the bloodstream, leading to symptoms such as jaundice. Unlike the other conditions listed, which can lead to both conjugated and unconjugated bilirubin elevation, the primary mechanism in hemolytic anemia strictly affects the unconjugated fraction.

Obstructive jaundice, hepatitis, and hepatic cirrhosis can lead to elevated levels of conjugated bilirubin due to issues with the liver's processing capacity or bile duct obstruction, causing a buildup of conjugated bilirubin in the bloodstream. In contrast, hemolytic anemia remains distinct in its sole impact on unconjugated bilirubin levels.