Sunitinib induces hypothyroidism with a markedly reduced vascularity.
BACKGROUND
Sunitinib is a small molecule that inhibits receptor tyrosine kinases, including the vascular endothelial growth factor receptors, and exhibits antiangiogenic and antitumor activity. This molecule has also been reported to cause hypothyroidism at a high frequency, but the mechanism of this is unknown.


CONCLUSIONS
A 60-year-old woman was administered sunitinib for the treatment of metastatic renal cell carcinoma. One week later, she displayed overt hypothyroidism with an atrophic thyroid and a marked reduction in vascularity as determined by ultrasonography, despite high levels of thyrotropin. In contrast, during the off-periods in the sunitinib treatment cycles, the volume of her thyroid recovered with an increase in vascularity despite a low level of thyrotropin. These results suggest that thyroid function and volume may depend on the vascularity, which is negatively regulated by sunitinib.


CONCLUSIONS
Our case study provides compelling evidence that sunitinib induces hypothyroidism by reducing blood flow via capillary regression and constriction.
Makita
Noriko
N
Department of Endocrinology and Nephrology, The University of Tokyo School of Medicine, Tokyo, Japan. norimaki-tky@umin.ac.jp
Miyakawa
Megumi
M
Fujita
Toshiro
T
Iiri
Taroh
T
D000970:Antineoplastic Agents / Q000009:adverse effects; D002292:Carcinoma, Renal Cell / Q000188:drug therapy* / Q000473:pathology; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000139:chemically induced* / Q000473:pathology; D007211:Indoles / Q000009:adverse effects*; D007680:Kidney Neoplasms / Q000188:drug therapy* / Q000473:pathology; D008875:Middle Aged; D009929:Organ Size; D011758:Pyrroles / Q000009:adverse effects*; D000077210:Sunitinib; D013961:Thyroid Gland / Q000098:blood supply / Q000187:drug effects / Q000473:pathology*
D000970:Antineoplastic Agents; D007211:Indoles; D011758:Pyrroles; D000077210:Sunitinib