What is the expected metabolite for heroin on confirmatory testing?

Heroin is metabolized in the body to form various metabolites, one of which is 6-monoacetylmorphine, commonly referred to as 6-MAM. This metabolite is significant because it is a unique marker of heroin use and can be detected in urine tests, distinguishing heroin use from the consumption of other opioids. Unlike the metabolites of other opioids such as morphine or codeine, 6-MAM typically will not be present after the metabolism of those substances. Therefore, in confirmatory testing for heroin, the presence of 6-MAM is expected and is an important laboratory finding that indicates recent heroin use.

The other options represent other opioid medications or their metabolites and would not typically appear in a heroin confirmatory test. For example, hydromorphone and oxymorphone are products of the metabolism of different opioids and do not indicate heroin use, while codeine is a naturally occurring opioid that, although it can come from heroin, is not a direct metabolite of heroin itself. The unique identification of 6-MAM makes it the correct choice in this context.