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Association between excessive urinary iodine excretion and failure of radioactive iodine thyroid ablation in patients with papillary thyroid cancer.
Thyroid 2013; 23(6):741-7T

Abstract

BACKGROUND

A low-iodine diet (LID) is usually recommended for a week or two before radioactive iodine (RAI) ablation therapy in papillary thyroid cancer (PTC) patients after total thyroidectomy. However, it is still controversial whether an LID affects ablation outcomes. We therefore evaluated the association between urinary iodine excretion and the rate of successful ablation and investigated the determinants of successful RAI ablation outcomes.

METHODS

We retrospectively reviewed the records of 295 consecutive patients with PTC who received 1110 MBq RAI remnant ablation therapy with thyroid hormone withdrawal after total thyroidectomy. Successful ablation was defined as either no visible or faint uptake on a follow-up scan (definition 1), or no visible or faint uptake on a follow-up scan and a stimulated thyroglobulin level <2 ng/mL (definition 2).

RESULTS

The proportion of patients with appropriate LID status (defined as a urinary iodine concentration [UIC] <66.2 μg iodine/g creatinine [μg/gCr]) was significantly higher in the successfully ablated group (81% vs. 67%, p=0.03). Based on definition 1, 80.3% (237/295) of patients were successfully ablated. The ablation rate was significantly lower in patients who had a UIC >250 μg/gCr at the time of RAI ablation (p<0.05). In multivariate analysis, a UIC >250 μg/gCr was the only significant variable associated with ablation failure (p=0.002, odds ratio [OR] 4.74 [95% confidence interval (CI) 1.78-12.63]). Based on definition 2, 74.9% (221/295) of patients were successfully ablated. A UIC >250 μg/gCr at RAI administration showed a significant association with ablation failure (p<0.05). The OR of a UIC >250 μg/gCr for ablation failure was 3.88 [CI 1.42-10.57] (p=0.008).

CONCLUSION

Excessive iodine intake (UIC >250 μg/gCr) was associated with poor RAI ablation outcomes. Because this amount of iodine is very high, we propose that the level of strictness of the LID protocol should be modified according to the region that the patient is from and the food that the patient is accustomed to eating. Even in those areas where iodine intake is high, overly strict compliance with an LID protocol is not necessary and simple recommendations to avoid iodine-rich foods would be appropriate.

Authors+Show Affiliations

Division of Endocrinology and Metabolism, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

23205883

Citation

Sohn, Seo Young, et al. "Association Between Excessive Urinary Iodine Excretion and Failure of Radioactive Iodine Thyroid Ablation in Patients With Papillary Thyroid Cancer." Thyroid : Official Journal of the American Thyroid Association, vol. 23, no. 6, 2013, pp. 741-7.
Sohn SY, Choi JY, Jang HW, et al. Association between excessive urinary iodine excretion and failure of radioactive iodine thyroid ablation in patients with papillary thyroid cancer. Thyroid. 2013;23(6):741-7.
Sohn, S. Y., Choi, J. Y., Jang, H. W., Kim, H. J., Jin, S. M., Kim, S. W., ... Kim, S. W. (2013). Association between excessive urinary iodine excretion and failure of radioactive iodine thyroid ablation in patients with papillary thyroid cancer. Thyroid : Official Journal of the American Thyroid Association, 23(6), pp. 741-7. doi:10.1089/thy.2012.0136.
Sohn SY, et al. Association Between Excessive Urinary Iodine Excretion and Failure of Radioactive Iodine Thyroid Ablation in Patients With Papillary Thyroid Cancer. Thyroid. 2013;23(6):741-7. PubMed PMID: 23205883.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Association between excessive urinary iodine excretion and failure of radioactive iodine thyroid ablation in patients with papillary thyroid cancer. AU - Sohn,Seo Young, AU - Choi,Joon Young, AU - Jang,Hye Won, AU - Kim,Hye Jeong, AU - Jin,Sang Man, AU - Kim,Se Won, AU - Suh,Sunghwan, AU - Hur,Kyu Yeon, AU - Kim,Jae Hyeon, AU - Chung,Jae Hoon, AU - Kim,Sun Wook, PY - 2012/12/5/entrez PY - 2012/12/5/pubmed PY - 2014/1/29/medline SP - 741 EP - 7 JF - Thyroid : official journal of the American Thyroid Association JO - Thyroid VL - 23 IS - 6 N2 - BACKGROUND: A low-iodine diet (LID) is usually recommended for a week or two before radioactive iodine (RAI) ablation therapy in papillary thyroid cancer (PTC) patients after total thyroidectomy. However, it is still controversial whether an LID affects ablation outcomes. We therefore evaluated the association between urinary iodine excretion and the rate of successful ablation and investigated the determinants of successful RAI ablation outcomes. METHODS: We retrospectively reviewed the records of 295 consecutive patients with PTC who received 1110 MBq RAI remnant ablation therapy with thyroid hormone withdrawal after total thyroidectomy. Successful ablation was defined as either no visible or faint uptake on a follow-up scan (definition 1), or no visible or faint uptake on a follow-up scan and a stimulated thyroglobulin level <2 ng/mL (definition 2). RESULTS: The proportion of patients with appropriate LID status (defined as a urinary iodine concentration [UIC] <66.2 μg iodine/g creatinine [μg/gCr]) was significantly higher in the successfully ablated group (81% vs. 67%, p=0.03). Based on definition 1, 80.3% (237/295) of patients were successfully ablated. The ablation rate was significantly lower in patients who had a UIC >250 μg/gCr at the time of RAI ablation (p<0.05). In multivariate analysis, a UIC >250 μg/gCr was the only significant variable associated with ablation failure (p=0.002, odds ratio [OR] 4.74 [95% confidence interval (CI) 1.78-12.63]). Based on definition 2, 74.9% (221/295) of patients were successfully ablated. A UIC >250 μg/gCr at RAI administration showed a significant association with ablation failure (p<0.05). The OR of a UIC >250 μg/gCr for ablation failure was 3.88 [CI 1.42-10.57] (p=0.008). CONCLUSION: Excessive iodine intake (UIC >250 μg/gCr) was associated with poor RAI ablation outcomes. Because this amount of iodine is very high, we propose that the level of strictness of the LID protocol should be modified according to the region that the patient is from and the food that the patient is accustomed to eating. Even in those areas where iodine intake is high, overly strict compliance with an LID protocol is not necessary and simple recommendations to avoid iodine-rich foods would be appropriate. SN - 1557-9077 UR - https://www.unboundmedicine.com/medline/citation/23205883/Association_between_excessive_urinary_iodine_excretion_and_failure_of_radioactive_iodine_thyroid_ablation_in_patients_with_papillary_thyroid_cancer_ L2 - https://www.liebertpub.com/doi/full/10.1089/thy.2012.0136?url_ver=Z39.88-2003&amp;rfr_id=ori:rid:crossref.org&amp;rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -