A Novel Tyrosine-Kinase Selective Inhibitor, Sunitinib, Induces Transient Hypothyroidism by Blocking Iodine Uptake

Abstract

A high prevalence of hypothyroidism, very severe in some cases, was observed during sunitinib. Significant variations in (123)I uptake strongly suggest that the underlying mechanism is an impaired iodine uptake. The absence of thyroid autoimmunity, the lack of a preceding transient hyperthyroidism, and the normal echographic pattern exclude autoimmune and/or destructive mechanisms. Patients on sunitinib should be strictly monitored for the appearance of hypothyroidism and promptly treated.