title: Transient Hypothyroidism after Radioiodine for Graves' Disease: Challenges in Interpreting Thyroid Function Tests.
abstract: Graves' disease is the most common cause of hyperthyroidism and is often managed with radioactive iodine (RAI) therapy. With current dosing schemes, the vast majority of patients develop permanent post-RAI hypothyroidism and are placed on life-long levothyroxine therapy. This hypothyroidism typically occurs within the first 3 to 6 months after RAI therapy is administered. Indeed, patients are typically told to expect life-long thyroid hormone replacement therapy to be required within this timeframe and many providers expect this post-RAI hypothyroidism to be complete and permanent. There is, however, a small subset of patients in whom a transient post-RAI hypothyroidism develops which, initially, presents exactly as the typical permanent hypothyroidism. In some cases the transient hypothyroidism leads to a period of euthyroidism of variable duration eventually progressing to permanent hypothyroidism. In others, persistent hyperthyroidism requires a second dose of RAI. Failure to appreciate and recognize the possibility of transient post-RAI hypothyroidism can delay optimal and appropriate treatment of the patient. We herein describe five cases of transient post-RAI hypothyroidism which highlight this unusual sequence of events. Increased awareness of this possible outcome after RAI for Graves' disease will help in the timely management of patients.
authors: Department of Endocrinology, Marshfield Clinic, Weston, WI, USA sheehan.michael@marshfieldclinic.org.
authors: Michael T
authors: MT
authors: Sheehan
authors: Research School of Population Health, Australian National University, Acton, Canberra, Australia.
authors: Suhail A R
authors: SA
authors: Doi
mesh_terms: D000328:Adult; D018450:Disease Progression; D005260:Female; D006111:Graves Disease / Q000150:complications* / Q000532:radiotherapy*; D006801:Humans; D007037:Hypothyroidism / Q000139:chemically induced*; D007457:Iodine Radioisotopes / Q000009:adverse effects* / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D013960:Thyroid Function Tests; D013961:Thyroid Gland / Q000000981:diagnostic imaging*; D013963:Thyroid Hormones / Q000378:metabolism; D013974:Thyroxine / Q000627:therapeutic use; D016896:Treatment Outcome
chemical_list: D007457:Iodine Radioisotopes; D013963:Thyroid Hormones; D013974:Thyroxine
keywords: Graves disease; Hypothyroidism; Radioiodine therapy; Thyroid hormones; Treatment outcome