Why might liver function tests be elevated in heart failure?

Elevated liver function tests in the context of heart failure are primarily attributed to passive congestion of the liver. In heart failure, the heart's ability to pump blood effectively is compromised, leading to increased pressure in the venous system. This is particularly evident when the right side of the heart is affected, causing blood to back up into the hepatic veins and subsequently the liver.

This back pressure hinders blood flow and disrupts normal liver function, leading to the release of liver enzymes into the bloodstream, which manifests as elevated liver function tests. It is important to understand that while other factors can influence liver function tests, the primary mechanism in heart failure is the passive congestion caused by impaired venous return rather than direct liver disease, reactions to medications, or unrelated conditions such as diabetes.