Presumptive tests in serology indicate what?

• A. Tests that indicate the possible presence of a substance
• B. Tests that definitively identify a substance
• C. Tests that measure exact concentrations
• D. Tests that determine the age of a sample

Answer: (A)

Presumptive tests in serology are screening tools that suggest the possible presence of a substance rather than providing a definite identification. They’re designed to be quick and sensitive, giving a positive result if the target may be present, but their results aren’t specific enough to confirm what exactly is there. Because they can yield false positives from other substances or conditions, a follow-up confirmatory test is needed to establish identity. They also don’t measure exact quantities, nor can they determine the age of a sample. For example, a presumptive test for blood may change color if blood is present, but that signal alone doesn’t prove it’s blood without additional confirmatory testing.