Lp(a) results using unexpected units

I live in the US and recently did my Lp(a) through Labcorp.

The results seem very good (8.4) but I was surprised to see the result was in nmol/L.

As I look for information on the Web, the vast majority of it seems to talk about values in mg/dL, which is what pretty much all of my tests seem to be in.

Okay, so time to lean how to convert, right? This is apparently much more complicated than expected. For starters, it apparently depends on which test you are converting. And there isn't a lot of information on converting Lp(a). And even information I found on converting Lp(a) gave me a range! It said to divide the nmol/L number but approximately 2.15 to 2.4.

Questions:

1. Does anyone know why Labcorp my use different units for just this one test?

2. Why isn't there a standard conversion to mg/dL?