Review Question - QID 214639

A 6-year-old boy is brought to the emergency department from school after he was found to have severe muscle weakness and cramps during recess on a hot, sunny day. On presentation, he complains of diffuse pain in his muscles bilaterally. His parents say that he was born at home at term with the help of a midwife, but he is up to date on vaccines and has met all of his developmental milestones on time. They note that he occasionally complains of muscle pain after mild exertion but they thought that it was just growing pains. He recently had an upper respiratory tract infection that was symptomatically treated. On presentation, he is found to have dark urine that tests positive for blood on a urine dipstick test; however, urinalysis does not reveal any red blood cells or fragments. Which of the following would most likely be seen in this patient?