Final answer:
An indication of a potential complication is a C-reactive protein of 1.4 mg/L (Option C), which suggests inflammation or infection post-surgery.
Step-by-step explanation:
The laboratory finding that should be identified as an indication of a potential complication in a school-age child who is 1 week postoperative following an open fracture repair is c) C-reactive protein 1.4 mg/L. This level is elevated and can be indicative of inflammation or infection, which are potential complications following surgery and fracture repair. The other values, including erythrocyte sedimentation rate (ESR) of 18 mm/hr, WBC count of 6,200/mm3, and RBC count of 4.7 million/mm3, are within normal ranges and do not suggest an immediate complication. Elevated C-reactive protein (CRP) is a marker of an acute phase reactant produced by the liver in response to inflammation, and an increase can indicate infection or other inflammatory processes that may require further intervention.