Following multiple reports that “Gossip Girl” star Michelle Trachtenberg had a liver transport sometime before her death Wednesday at age 39, fans have wondered why she would have needed such an serious operation.

Trachtenberg’s cause of death has not officially been released and is pending an autopsy by the New York City medical examiner’s office, Officials say the former child actor was found unconscious and unresponsive in her Manhattan apartment at around 8 a.m.

Trachtenberg’s rep, Gary Mantoosh, would not release “further details at this time,” as he released a statement saying, “It is with great sadness to confirm that Michelle Trachtenberg has passed away. The family requests privacy for their loss.”

Sources have told , and that she had recently undergone a liver transplant and may have been experiencing complications. This possibility has prompted many online to ask why a relatively young woman like Trachtenberg would need a new liver and to wonder if she had been struggling with health issues in recent years.

Until friends, family or officials come forward to confirm that she had, in fact, undergone a liver transplant, say whether it played a role in her death, or to explain any health issues leading up to the reported operation, here is what top U.S. health experts say about why people usually need new livers.