Q. Please advice the relation between urine drug test and hair follicle test.

Answered by
Dr. Arul Amuthan
and medically reviewed by Dr.Nithila A
This is a premium question & answer published on Aug 08, 2019

Hello doctor,

I am trying to figure out the conversation between levels on a urine drug test and a hair follicle test. For example,

Urine test: 505 ng/ml THCA.

Hair test: 5.95 pg/mg THCA .

If there were 32.6 ng/ml cocaine metabolite detected in a urine test, how might that show in a hair drug test? There seems to be a correlation between the THCA levels, but I cannot figure out what the connection might be?

Dr. Arul Amuthan

Ayurveda Specialist Naturopathy Pharmacology Siddha Medicine Toxicology


Welcome to icliniq.com.

In the urine, the metabolites are detected as it is directly coming out from the blood. I mean, it gives a day to day excretion of the metabolite, that is directly proportional to the amount of the specific drug or metabolite in the blood. Whereas, the metabolites or drugs in the hair tells the history of any drug or chemical usage. As we know, the growth of hair is very, minimal daily.

Certain chemicals or drugs or metabolites can get accumulated in the hair on a long term basis. So, if we could find the THCA (tetrahydrocannabinolic acid) in hair, it is telling the past blood concentration or usage of the THCA. Thus, the hair value may not usually proportional to urine values. I hope I have answered.

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