Re: Can't get PSA to zero
When you get the lab test results back, it will show the normal range for that test kit. His DHT level should be below that. If it's not, why not see if Avodart brings it down? Ideally, it might have been useful to have had his own baseline DHT level taken before he started on ADT, so you could detect the degree of DHT inhibition from his ADT alone and by adding Avodart to the mix.
According to one source, normal levels are between 23-73 ng/dl (.8-2.5 nmol/L).
[This is based on the full text article available here: http://www.ncbi.nlm.nih.gov/pubmed/15901667]
But you should use the lab's definition of "normal" if they provide it.