Final answer:
A practical nurse must inquire about any history of hormone-sensitive cancers, thromboembolic disorders, liver disease, or current pregnancy before administering conjugated estrogens to ensure the safety of the medication.
Step-by-step explanation:
The practical nurse (PN) is obtaining the medical history of a female client starting a new prescription for conjugated estrogens (Premarin) 0.625 mg PO daily. The most important information for the PN to obtain from the client before taking the first dose of the medication is whether the client has any history of hormone-sensitive cancers, thromboembolic disorders, liver disease, or if she is currently pregnant. These conditions can be significantly affected by the introduction of exogenous estrogens, which could lead to serious complications or contraindications.