Yes, there is a urine test I believe. But you know, the reports on PubMed that I found for the two patients with loss of taste,
tested NORMAL on biotin and the doctors gave high doses anyway and they improved.
So the actual Biotin understanding remains murky. I don't think it is worth testing for, if the tests don't reflect biological resistance to it.
Here is a nice WebMD explanation, stating testing is not accurate.
I've been thinking about this quite a bit.... it could be some people here are marginal on biotin activity and that is contributing to their PN symptoms. It appears that biotin is very safe and inexpensive and worth a try. It would have to be high dose, and taken away from any lipoic acid or high dose B-complex because of the B5 content.
I just received my 5mg from my yearly Puritan's purchase. And I just increased to 10mg at night after 5 days of 5mg.