Final answer:
Methylprednisolone decreases potassium levels through urinary excretion. The nurse should instruct the client to increase dietary potassium intake.
Step-by-step explanation:
Methylprednisolone decreases potassium levels through urinary excretion. Therefore, the nurse should instruct the client to increase dietary potassium intake. This will help maintain the normal potassium concentration in the body. Consuming potassium-rich foods can help offset the decrease in potassium caused by the medication.