Hair or Saliva for Drug Testing

Urine is currently the most widely used and extensively validated biologic specimen for drug testing [21, 59, 66]. Although alternative technologies using other biologic specimens are marketed for drug testing, information is lacking about false-positive

Negative

Positive

Negative

Positive

Every discoloration indicates alcohol in the specimen. The darker the color intensity, the higher the alcohol concentration in the sample.

No alcohol can be detected in the specimen

Every discoloration indicates alcohol in the specimen. The darker the color intensity, the higher the alcohol concentration in the sample.

Figure V-15. View of the test stick for alcohol and the color, which reflect a positive analysis

Table V-8. Summary of pros ad cons for using saliva and and/or hair for drug testing

Saliva

Hair

Advantages

• Collection ease

• Minimal invasiveness

• Close supervision

• Limited preanalytical manipulation Disadvantages

Advantage

• Long-term measure related to hair length Disadvantages

• Dark hair greater capacity to bind drug

• Irregular growth

• Accessibility

• Shorter retention, lower levels than typically in urine • Labor-intensive sample preparation and false-negative results, interferences, and cross-reactivity. At this point, most of these techniques may not be appropriate for use in clinical practice [62].

Factors that influence the selection of a biologic specimen for drug analysis include ease of collection, analytical and testing considerations, and interpretation of results [80, 81]. Advantages of saliva as a test sample include ease of collection, minimal personal invasiveness, collection under close supervision (preventing tampering with the sample), and limited preanalytical manipulation (Table V-8). However, drugs and their metabolites are retained for shorter periods and occur at lower concentrations compared with urine [63, 80-82].

Hair analysis provides a retrospective, long-term measure of drug use that is directly related to the length of hair [66, 81]. Hair analysis is most useful for rapidly excreted drugs like heroin and cocaine, where the likelihood of drug misuse remaining undetected by urine analysis is substantial [66]. However, darkly pigmented hair has a greater capacity to bind a drug than hair that is fair or gray, leading to the claim that hair analysis might have a possible color bias [21, 81]. Other disadvantages of hair analysis include possible irregular growth, accessibility, and labor-intensive sample preparation.

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