Hi Nicky,
yes there are so many tests available, I usually ask the lady taking the blood if my Dr puts a new one on my list.
this is a great website I found ages ago and exlplains about lab tests. Hope its helpful, I did look for CPK on the Aussie website, but couldn't find it. May be it will be on the US site, I think you can access from it.
http://labtestsonline.org.au/understanding/index.html
take care
Kate