Final answer:
The nurse should schedule the toddler for a yearly rescreening because the serum lead level of 4 mcg/dL is below the action level of 5 mcg/dL. There is no current need for chelation therapy or a dietary change, and a referral to child protective services is not warranted based on the information provided.
Step-by-step explanation:
Given that the toddler's serum lead level is 4 mcg/dL, which is below the CDC’s recommended action level of 5 mcg/dL, the nurse should schedule the toddler for a yearly rescreening. Chelation therapy is generally reserved for blood lead levels greater than 40-45 µg/dL, and thus is not appropriate at the level reported. There is no indication from the given information to decrease dietary calcium; in fact, nutrients like calcium can help protect against lead toxicity. Referral to child protective services would be unnecessary in the absence of indications of neglect or abuse. Monitoring for developmental delays is essential as well, due to the potential for lead exposure to cause long-term effects despite the current blood level being below the action threshold.