HI Fuzzyhead,
I don't know of any sites. However there is an interesting study done in the UK on treating peripheral neuropathy with MeCbl (2 doses, 120mcg or 1500mcg to test dose proportionality). This study admitted son the basis of symptoms, not test results. It turns out 62% of the RESPONDERS would not have been allowed in based on test results, their levels were "too high" to qualify. The average in the study was 700+pg/ml at the start with the highest being over 1500pg/ml. There are any number of journal studies saying why the tests are not predictive of who will benefit form MeCbl and/or AdoCbl, that only a trial can answer that question. And since there is no testing done of cerebral spinal fluid for cobalamin, Hcy or MMA there is no way of knowing if those are affected and they can be low CSF cobalamin when the body is high. They are separate compartments. If they did a uMMA then at least you would know if you are so low on AdoCbl that the house is burning down. However, there is no number that means sufficiency or asymptomatic. You are caught up on a essentially meaningless number. The studies could be found with Google scholar with some looking.