Sunitinib-induced severe hypothyroidism with cardiac compromise.

Tyrosine kinase inhibitors (TKI) are an increasingly used class of anti-cancer agent. Sunitinib (sutent(®), Pfizer™, New York) is standard first-line therapy for patients with metastatic renal cancer. It is associated with a number of toxicities, including thyroid dysfunction. We present a case of sunitinib-induced severe hypothyroidism resulting in cardiac compromise. The case highlights the importance of interval thyroid function monitoring for patients on drugs, such as sunitinib and other TKIs.