Clinical and Laboratory Standards Institute guideline C52— Toxicology and Drug Testing in the Medical Laboratory helps medical laboratories develop procedures for analyzing drugs of abuse and other compounds. C52 provides guidance on clinical toxicology testing from the initial consultation through final result reporting and interpretation, and includes a variety of specimen types, analytical procedures, and instrumentation. This guideline discusses the most common purposes for clinical toxicology testing, including the support of emergency medicine, obstetrics and gynecology, neonatology, pediatrics, psychiatry, pain management, and addiction medicine. The primary objective is to ensure high-quality standards are maintained throughout the entire testing process, from specimen collection, processing, and analysis, through results reporting and interpretation.

This guideline replaces the previous edition of the approved guideline, C52-A2, published in 2007. Several changes were made in this edition, including: 

• Focusing the guideline exclusively on clinical toxicology testing (in contrast to previous editions of C52, which focused extensively on clinical and forensic testing for drugs of abuse) 

• Removing forensic testing, to avoid redundancy with forensic testing recommendations published by forensic organizations

This guideline provides laboratories with basic and general toxicology testing information for medical purposes. The guideline discusses the most common specimen types used for toxicology testing, which include urine, serum, plasma, blood, oral fluid, hair, meconium, sweat, and breath. Other matrixes that can be used for toxicology testing include, but are not limited to, gastric contents, umbilical cord and cord blood, amniotic fluid, breast milk, nails, dried blood spots, and placental tissue. However, these other matrixes are not discussed in this guideline. 

The measurands considered in this guideline include drugs of abuse, therapeutic drugs, over-the-counter (OTC) medications, ethanol, and miscellaneous substances. Test methodologies include rapid screening measurement procedures designed to produce only positive or negative results (qualitative tests), routine semiquantitative and quantitative tests, and more complex definitive measurement procedures. C52 also provides useful guidance when performing drug testing for measurands other than those specifically included and for purposes and situations not covered. 

This guideline is primarily applicable to drug testing performed in medical laboratories. The information is likely applicable for drug testing performed in physician office laboratories, clinics, satellite laboratories, and other facilities, but may be less applicable in other testing venues, such as large specialized reference laboratories, dedicated forensic laboratories, and the various sites in which point-of-care “field testing” may occur.