The window of collection for the urine sample for a drug screen should be as short as possible after exposure within 8 to 12 hours of removal. Cases exist in which children in clandestine labs have been exposed either deliberately or inadvertently to drugs and medications other than methamphetamine. A urine drug of abuse screen detects some classes of commonly abused drugs. However, many harmful chemicals with which a child may come in contact in a clandestine lab will not be detected by such a screening tool. Urine drug screening may be performed at the discretion of the treating medical providers who understand its strengths and limitations. However, in cases of unresolving tachycardia or signs of sympathetic excess of unclear etiology, a drug screen might be useful. In completely asymptomatic children, a urine drug screen may be beneficial for prosecutorial efforts. Given the fact that some studies have shown greater that 50% of these children test positive for methamphetamine, the current recommendation is for urine drug screening to be performed. False positive results for amphetamines on screening tests are common and any positive screening result should be confirmed prior to legal action being initiated. Medical care should not be delayed while waiting for confirmation of screening results as confirmatory testing may take several days.
It should be emphasized, however, that all children should be considered exposed to methamphetamine or other drugs of abuse if found in a clandestine laboratory regardless of the urine drug screen results. All urine drug screens must be followed by confirmatory testing using GCMS. If performed, hair and skin-patch testing should be performed in consultation with a knowledgeable authority who understands the methodology strengths and limitations. Legal chain of custody procedures must be followed at all times for specimens obtained for drug testing.