Quantitative urine levels of cocaine and other substances of abuse.

Used appropriately, quantitative levels can address research hypotheses and clinical issues that are otherwise untested by traditional qualitative urine results. Quantitative urine levels can provide new information in health services research, pharmacotherapy trials, studies of the interaction of cigarette smoking and substance abuse, additional studies of polysubstance abuse, and the linking of biological markers with phases of addiction and risk to relapse.