Investigation of Drug Screening
The Court had restricted a father's visitation with his young child due to the father's drug use. At issue was his ability to take care of the child when in his care. His visitation was conditional on passing random drug screen tests. The urine collections were carried out through a company that specialized in facilitating drug screening for court ordered testing. The process began with a phone call to the father to meet a collector at a suitable location within four hours. The urine sample was then shipped to a commercial laboratory by the collector. Resulting drug screens from the father were reported negative. Family members were suspicious that the father was still doing drugs. This consultant was asked to review the drug screen results for potential errors.
Most of the laboratory reports included a footnote that the creatinine was below the laboratory's criteria for suitable specimen. This footnote was not understood by the collector, results were then misinterpreted, and subsequently reported as a "negative" drug screen to the court. Every other laboratory result, except one, reported a very low creatinine concentration. The creatinine results indicated the father was diluting his urine by drinking excessive amounts of water. The four hour period gave him more than enough time to drink sufficient fluids to produce negative drug screens. The one drug screen with a normal creatinine was collected on the spot without prior warning.
Published literature indicated that a person can dilute a drug positive urine to levels below cutoffs, by drinking three to four liters of fluids. Laboratory regulations require cutoffs for drug screens. Thus, a urine specimen may contain drugs, but if the levels are below Federal mandated cutoffs, a "negative" result will be reported. Even when confirmations are done, cutoffs are still required. Most commercial laboratories will report results, in spite of detected dilution (i.e. low creatinine), qualifying results with a footnote. If the person interpreting results is not aware or familiar with creatinine levels, the results can be misinterpreted.
This consultant was asked by the Court to design a monitoring program that would overcome the father's practice of dilution. This consultant recommended that urine specimens continue to be collected at random times. This consultant eliminated the routine drug screen that provides qualitative results, based on cutoffs. Instead, the urine specimen would be tested by GCMS or LCMSMS for quantitative levels of a wide spectrum of street and prescription drugs. No cutoffs were employed and the presence and amount of any drug was reported. Interpretation would be provided by a toxicologist in case the presence any drug detected was justified or legal. Detection levels of mass spec are low enough to eliminate the ability of fluid intake to prevent detection.
This consultant was asked to present this case and other similar cases of misinterpreted drug screens to the Southwestern Association of Toxicologists meeting. Slides are available.
To see the resume of the expert associated with this case study, see the link below.
