There is a full-blown, high-quality peer-review process for a thesis: it's called the thesis committee.
If you mean a service where you can get help improve your document before you submit it to your committee, that is something that one's advisor(s) tasks. Maybe you can actually get help from friends, colleagues, or in the most severe cases your advisor's friends, but there is not much.
The thing that may be closely related is that, in some systems (the French one at least), there is a person that is responsible for validating the PhD student's manuscript before it gets sent to the committee. Then, it's that person's responsibility (in theory) to do a basic check of your manuscript and your work, and decide if there is enough to gather a committee. I say “in theory”, because this person will probably get dozens of theses per year (at the very least) and can only perform the most basic checks. In practice, they most often do not check the manuscript content, but its form (does it follow the University's standards), as well as some simple indicators of your research (has the candidate published? how many times? did he attend conferences? that sort of stuff).