Final answer:
When a patient takes levothyroxine and warfarin concurrently, the nurse monitors for increased bruising due to elevated metabolism affecting warfarin's anticoagulant action. The correct option is D.
Step-by-step explanation:
For a patient taking levothyroxine (Synthroid) and warfarin (Coumadin) concurrently, the nurse would closely monitor for the possible serious adverse effect of increased bruising. Levothyroxine is a thyroid hormone replacement used to treat hypothyroidism.
It can elevate the body's metabolism and potentially enhance the effects of warfarin, which is an anticoagulant (blood thinner). Increased metabolism may lead to higher rates of warfarin metabolism and an elevated INR (a measure of blood clotting), which increases the risk of bleeding and subsequently, bruising.
Other options such as acute confusion, cardiac dysrhythmias, and orthostatic hypotension are also concerns with these medications but not the primary concern when these two medications are used concurrently. Option D. is the correct one.