What type of test is an ELISA?

An ELISA, or Enzyme-Linked Immunosorbent Assay, is indeed classified as a quantitative in vitro test. This test is primarily used to detect and quantify proteins, antibodies, hormones, and other substances in a sample, often related to disease diagnosis or monitoring. The "quantitative" aspect refers to its ability to measure the concentration of analytes, which can be expressed in specific units such as ng/mL or IU/mL.

Being an "in vitro" test means it is performed outside the living organism, usually in a laboratory setting using samples like blood or other bodily fluids. This method employs antigen-antibody interactions and often includes steps that involve binding, washing, and detection using enzymes that produce measurable signals.

In contrast, options involving genetic tests or psychological assessments do not fit the operational procedures or purpose of an ELISA. Similarly, a physical examination is a hands-on assessment conducted by a healthcare practitioner rather than a laboratory-based analysis of samples. Thus, the classification of ELISA as a quantitative in vitro test accurately reflects its design and intent within medical diagnostics.