What route should the nurse use to administer purified protein derivative (PPD) to a client?

The purified protein derivative (PPD) test, commonly known as the tuberculin skin test, requires the PPD to be administered intradermally. This method involves injecting a small amount of the substance just beneath the top layer of the skin, typically on the forearm. The intradermal route allows for a localized immune response that can be assessed visually after 48 to 72 hours, making it the most effective method for interpreting reactions to the test.

Using other routes such as intravenous, intramuscular, or subcutaneous would not provide the appropriate conditions for the test. An intravenous injection would disperse the PPD throughout the bloodstream rather than allowing for a localized reaction. Similarly, an intramuscular injection might provoke a different immune response that is not suitable for this specific skin test. A subcutaneous injection, while it delivers the substance beneath the skin, does not provide the exact placement needed for an accurate interpretation of the results like the intradermal route does.