A 45-year-old male with bipolar I disorder has been taking divalproex sodium 1000 mg daily for nine months with good mood stabilization. At his routine monitoring visit, laboratory results reveal an AST of 62 U/L (normal: 10-40), ALT of 78 U/L (normal: 7-56), GGT of 55 U/L (normal: 9-48), and total bilirubin of 0.9 mg/dL (normal: 0.1-1.2). His valproic acid level is 85 mcg/mL (therapeutic: 50-125). His albumin is 3.9 g/dL, platelet count is 195,000/microL, and INR is 1.0. He reports no abdominal pain, nausea, jaundice, or fatigue and feels well overall. He denies alcohol use and takes no other hepatotoxic medications. The PMHNP is evaluating the significance of these laboratory findings. Which of the following best represents the appropriate evaluation?