Which of the following tests may require a special chain of custody form?

A drug screen may require a special chain of custody form because it is essential to ensure the integrity of the sample during the testing process. A chain of custody form documents every step of the sample's handling, from collection through testing, to maintain accountability and prevent tampering or contamination. This meticulous documentation is crucial in legal and employment-related drug testing scenarios where the consequences of a false positive or negative can have significant implications.

In contrast, other tests, such as those for altitude sickness, glucose, and liver function, do not typically involve the same level of scrutiny or risk of manipulation that necessitates a formal chain of custody process, making them less likely to require such documentation.