A 42-yeаr-оld оbese mаle repоrts to the clinic to follow up on lаb results for a workup regarding chronic fatigue. The labs resulted as follows: Test Result Hemoglobin (Hgb) 18.2 g/dL Hematocrit (Hct) 58% RBC Count 6.2 million cells/μL WBC Count 9,200 cells/μL Platelet Count 500,000 cells/μL MCV (Mean Corpuscular Volume) 90 fL TSH (Thyroid Stimulating Hormone) 2.1 mIU/L A1C (Hemoglobin A1c) 5.4% Based on these results, you will order a _____ to further evaluate this patient’s fatigue.