Review Question - QID 212394

A 25-year-old African American man comes to the emergency department for “red urine.” Patient reports that he just returned from a skiing trip in the Rocky Mountains and developed the reddish urine today. He denies upper respiratory infection symptoms, chest pain, fever, or chills but does endorse some right flank pain that developed 3 days ago. Physical examination was unremarkable except for some tenderness upon palpation at the right flank. Laboratory findings are as follows:

Serum:
Na+: 137 mEq/L
K+: 4.9 mEq/L
Cl-: 100 mEq/L
HCO3-: 25 mEq/L
Osmolality: 275 Osm/kg

Urine:
Color: Red
Protein: 3+
RBC: 4 cells/hpf
Osmolality: 214 Osm/kg
Specific gravity: 1.004

Which finding would you most likely expect with this patient?