Final answer:
The nurse should prioritize evaluating the child's hepatic function, as an overdose of acetaminophen can cause serious liver damage, and the liver is the organ responsible for metabolizing the drug.
Step-by-step explanation:
If a 10-year-old child has been given adult doses of acetaminophen (Tylenol) at least twice a day and is experiencing chronic headaches, the priority function a nurse should evaluate is the child's hepatic function. Acetaminophen overdose can lead to severe liver damage or even death, particularly if dosages exceed recommended amounts. While all functions listed are important for overall health, the liver is the primary organ responsible for metabolizing acetaminophen, and therefore, it is at the highest risk when overdosing occurs.
It is crucial for healthcare providers to carefully monitor a child's medication regimen and ensure that dosages are appropriate for their age and weight to avoid potential toxicity. In pediatric patients, this is especially significant since their organs are still developing, and they might be more susceptible to the adverse effects of medications. Liver damage from acetaminophen is often treatable if identified early, emphasizing the importance of prompt assessment in such cases.