There's no such thing as a metabolism test.
What markers do you want to measure?
If It's general (not CFS) metabolism, maybe you mean a metabalon test the USA company do? If so, no one else does it, they patented it.
Or if you mean the CFS metabolism test discussed by Ron Davis he used on his son ages ago?. It's not commercially available, sorry. There was talk of this being available 'soon' (last year) as an apparent favour to the CFS community who follow the OMF research but this seems to have fizzled out unfortunately.
Maybe in 2019 we might get lucky, although I thought that in 1991 ...