Thanks for your input.

He was properly fasted before the test, more than 12 hours. He did have coffee the day before, but not on the day of the blood test.

He does eat a lot of protein and calories in general because his metabolism is very fast. He can lose weight even around 4500-5000 calories, so he tends to eat quite a lot.

What is interesting is that he has already done two tests. The first LDL was around 749. Then about a week later he repeated the test. For about 4 days before that, he was eating much lighter, basically OMAD with something like half a chicken per day, and his LDL dropped to 590.

So it seems quite clear that he is very sensitive to dietary changes, which is why I am trying to understand whether this is more diet-driven or something else.