A 19-year-old African American male with a history of bipolar I disorder presents to the psychiatrist for a follow-up visit. During the session, the patient explains that for the past 2 months he has felt significantly fatigued and constipated. He is always complaining of feeling cold and has gained several pounds although his diet has not changed. A blood sample was sent for analysis, revealing the following: TSH - 6 mIU/L (nl = 0.4-4.0 mIU/L), free T4 - 0.4 ng/dL (nl = 0.7-1.9 ng/dL), and serum T4 - 2.1 mcg/dL (nl = 4.6-12 mcg/dL). Which of the following is responsible for these abnormalities?
A. Valproic acid
B. Lithium
C. Carbamazepine
D. Lamotrigine
E. Olanzapine