I had the profile performed by IWDL in the UK. Their website is http://www.iwdl.net. You can order either a blood or urine profile directly without the need for a doctors referral. The essay is performed by Doctor's Data in the States and it is they who organise the production of the amino acid formula if you decide to proceed.
It is true that when digestion is worling properly there is probably no need to take pure amino acids, but it is claimed that if digestion has been direupted for some reason, amino's will help get it restarted. See a book written by Dr Robert Erdmann called the Amino Revolution, it is all explained in there.