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USDTL Research

Nail Samples Show Wider History of Drug Use Than Urine

Nail samples provide an excellent alternative sample matrix to urine. Some drugs that do not bind well in hair, like marijuana, are very stable in a nail matrix. Toenails are available for post-mortem drug testing when other body fluids are no longer present. Other benefits include a gender-neutral sample collection process and a reduced risk of adulteration. In 2006, USDTL introduced broad 5-, 7-, 9-, 12- and 14-drug panels for nail samples.

Nail samples are a similar matrix to hair, a keratinized protein, and therefore can be tested similarly. Drugs are incorporated into hair and nail samples at comparable levels. Drugs enter nails through nail matrix cells located at the base of each finger or toenail. Drugs are then distributed down the nail bed. Most people do not know that nails grow both in length and in thickness, with the free end of the nail being thicker than the lunula at the base of the nail. The nail grows in thickness by adding ventral layers.

Drugs present on the nail bed are incorporated into these layers. Drugs of abuse are measurable in nail samples approximately two weeks following ingestion. Fingernail samples can reflect drug usage over a six-month period. Toenails, growing at a slower rate, can identify drug usage in the previous 12-month period. Collecting either sample will give a much longer view of drug history than urine, oral fluid or blood. Nail testing also boasts a less demanding collection process than urine or blood.

Our Nail Drug Testing assay requires 100 milligrams of nail sample. The amount is equal to a 2 millimeter sample harvested from each finger. When a sufficient sample volume has been collected, the sample is transferred onto the collection foil and folded for security. The completed chain of custody form and the sample are sealed into the specimen collection bag.

The laboratory test procedure includes an immunoassay initial test combined with LC/ MS/MS or GC/MS confirmation of presumptive positive results. Screen negative results are typically reported within 24 hours of receipt into the laboratory, while confirmation of presumptive positives requires an additional 48 hours for confirmation.

USDTL’s Research and Development Department continues to develop nail tests in correlation with each new drug added to the growing hair test panel. In late 2009, researchers added ketamine to hair and nail panels after reports indicated an increase in ketamine abuse and fatal poisonings. For more information, contact Client Services at (800) 235-2367.


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