Quetiapine‐Induced Thyroid Dysfunction: A Systematic Review

Thyroid abnormalities are documented consequences of quetiapine treatment. This may have clinical implications as changes in thyroid hormones may deteriorate a person's affective state. Yet less is known about the clinical factors and underlying mechanisms associated with thyroid hormones on quetiapine therapy. We therefore systematically reviewed the published literature of evidence of quetiapine-induced thyroid abnormalities. We searched MEDLINE, PsycINFO, Google Scholar, and EMBASE for articles in which individuals developed biochemically confirmed thyroid abnormalities (with or without clinical symptoms) while on quetiapine treatment. We included case reports, case series, observational, and experimental studies. We included 32 studies, 20 of which were observational and experimental studies. There were 10 case reports and 1 case series. All the research designs suggested an association between quetiapine and hypothyroidism. However, these findings were limited by the quality of the included studies and the general lack of either a clear temporal relationship or dose response. Quetiapine has been associated with thyroid abnormalities, mainly with hypothyroidism. Drug imputability in these abnormalities is not always clear, and the underlying pathophysiology may include immunological and nonimmunological mechanisms. Large prospective studies are required to clarify this association and to further inform the management of patients treated with quetiapine where hypothyroidism occurs.