Final answer:
The nurse should advise the client to undergo liver function tests before obtaining a refill for the severe nodulocystic acne vulgaris prescription.
Step-by-step explanation:
The nurse should advise the client that liver function tests are required before obtaining a refill for severe nodulocystic acne vulgaris prescription. Since the prescription medications for severe acne can have potential side effects on the liver, it is important to monitor the liver function regularly. The liver function tests, such as alanine transaminase (ALT) and aspartate aminotransferase (AST), can indicate any liver damage or abnormalities.