Hello. I knew I was going to be taking a hair follicle test today through Quest Diagnostics, so exactly two weeks ago I had a personal HFT scheduled by Health Street at a Quest Diagnostics location. At the time of the test, I had not smoked marijuana for four weeks, but I had been a regular user for five months prior. Quest took a 1.5" hair sample, indicating approximately three months of use history (or 1 inch of "dirty" hair and .5 inches of "clean" hair). I had also been taking prescription Adderall for the 2-3 weeks leading up to the test.

My results came back negative for all five of the panel drugs, including the Marijuana metabolite THC-COOH and amphetamines despite the fact that I had ingested both during the test's detection window. I was on a relatively low dose of Adderall, so I wasn't too surprised to test negative. I was very surprised, however, to test negative for THC-COOH despite heavy use in the test's detection window. So anyway, I knew that I could test negative for an HFT, and everything seemed fine.

I prefer to have short hair, so after the first test but before my official one I cut it to right at Quest's minimum head hair length requirement of .5". I also trim my arm hair to about 1/4" every few weeks, but it was a little longer than that today. Long story short, I ended up giving them a testing sample of arm hair, although it did not meet the >.75" requirement for a body hair sample as required by my employer (a small portion of the hairs were around .5", but most were closer to .25"). As best as I can determine, this is roughly 3-4 weeks of arm hair growth, but with the caveat that body hair goes through wildly different anagen/telogen phases than head hair. The growth period for arm hair is 13 weeks, with only 20% of all arm hairs being in the growing phase at the same time.

So I have two questions:

1) What are the odds that the sample will be rejected by Quest's labs because of its length? I was able to verify through Quest's website that the minimum length of head hair that can be tested is .5", but I cannot find a minimum length for body hair of any kind. I emailed this question to Quest Diagnostics, but have not received an answer yet.

2) If I passed the first HFT with hair that had grown, for the most part, while I was using heavily, do I have similarly good odds of passing with "recently grown" arm hair?