From what I understand and I haven't seen this question in aout a year so I might be off but this is similar to the hair test. It's an alternative for someone who has no usable head or body hair and it consists of nair shavings. They use up to 1 & 1/2 inches of hair from the root but I don't know about nails. The only time I have heard about it offered was someone who was undergoing chemo. I forgot if he took it or got a urine test.