Final answer:
Patients taking lithium carbonate for bipolar disorder should have periodic thyroid function tests to monitor for potential impacts on thyroid health.
Step-by-step explanation:
If a client is taking lithium carbonate for the treatment of bipolar disorder, the nurse should recommend that the client undergo periodic thyroid function tests. Lithium can affect thyroid function, leading to either hypo- or hyperthyroidism, therefore, monitoring thyroid health is important in patients on lithium therapy. Regular monitoring through thyroid function tests can help detect changes early and allow for adjustments in treatment if necessary.