How to think about... liver function

One of the most common questions we get asked about medicines where there isn't a straight forward answer is how to work out whether a medicine is harming someone's liver, or whether someone's liver is affecting a medicine. For kidneys we have eGFR and CrCl. For liver we have LFTs. But why is it not that simple, and how can we start thinking about these sorts of questions to try to make it a bit simpler? This isn't a podcast about what a specific LFT means at specific levels (because - spoiler alert - LFTs don't work like that) but does try to give an overview of what sorts of things to think about and what common pitfalls might be.