In drug testing, what does a true positive result indicate?

In drug testing, what does a true positive result indicate?

• A. A sample is positive and the drug is truly present
• B. A sample is positive but the drug is not present
• C. A sample is negative but the drug is present
• D. A sample is negative and the drug is absent

Answer: (A)

A true positive means the test result is positive and the drug is actually present in the sample. It reflects an accurate detection, not a mistaken result due to cross-reactivity or interference. In practice, screening immunoassays can be very sensitive, but a positive screen is often followed by a confirmatory test (like GC-MS or LC-MS/MS) to verify the true presence of the specific drug. By contrast, a positive result with no drug present is a false positive, and a negative result when the drug is present is a false negative; a true negative is negative when no drug is present.

A true positive means the test result is positive and the drug is actually present in the sample. It reflects an accurate detection, not a mistaken result due to cross-reactivity or interference. In practice, screening immunoassays can be very sensitive, but a positive screen is often followed by a confirmatory test (like GC-MS or LC-MS/MS) to verify the true presence of the specific drug. By contrast, a positive result with no drug present is a false positive, and a negative result when the drug is present is a false negative; a true negative is negative when no drug is present.