Q31
Single choice
An 18-month-old boy is brought into the urgent care clinic by his mother who complains that he is "eating weird stuff." For the past few months since being able to walk, he has been found chewing and swallowing odd substances, such as hair, paper, and string. She has been more concerned since she recently noticed him eating clay from around the foundation of their apartment in the projects. His appetite has been affected because of this, and she is worried that he will become sick as a result.
Determination of which of the following blood levels would be the most appropriate next step in the workup and management of this patient?