Life-threatening hypothyroidism during thyroid hormone withdrawal for routine thyroid cancer surveillance

For patients with thyroid cancer, thyroid hormone withdrawal (THW) is commonly recommended during tumor surveillance. This process stimulates thyrotropin and thyroglobulin levels and maximizes the diagnostic sensitivity of radionuclide thyroid scans. THW, while generally regarded as safe, predictably generates a variety of adverse physical, psychologic, social, and economic consequences. In recent years, recombinant human thyrotropin (rhTSH) has emerged as a "preferred" alternative to THW, primarily since its use allows patients to avoid clinical hypothyroidism. With regard to sensitivity for detecting residual/recurrent thyroid cancer, rhTSH stimulation compares favorably to THW. However, the use of rhTSH for therapeutic doses of radioactive iodine remains largely investigational. This report describes a patient with poorly differentiated (papillary) thyroid carcinoma, who developed severe, life-threatening hypothyroidism during THW for routine tumor surveillance. This appears to be the first such case reported in the world's literature. This case reinforces the potential value of rhTSH (vs. THW) for thyroid cancer surveillance and supports the need for further research employing rhTSH for therapeutic doses of radioactive iodine.