This is an excellent question.

It is often surprising, but even extensive liver cysts do not generally cause liver failure, nor increases in liver enzymes.

There are scattered reports of patients who suffered liver functional problems and failure related to massive cyst replacement of normal liver tissue but it is rare.

I think the lesson here is that if a patient with ADPKD has liver enzyme rise or liver failure, another cause should be sought before attributing it to ADPKD.