RSNA 2014 

Abstract Archives of the RSNA, 2014


SSM19-04

The Effects of Age and Routine Dietary Iodine Consumption on Performance of Low Iodine Diet for rhTSH-aided Radioiodine Ablation for Papillary Thyroid Cancer

Scientific Papers

Presented on December 3, 2014
Presented as part of SSM19: Nuclear Medicine (Gastrointestinal and Endocrine)

Participants

Kunihiro Nakada, Presenter: Nothing to Disclose
Mika Tamura BS, Abstract Co-Author: Nothing to Disclose
Masayuki Sakurai, Abstract Co-Author: Nothing to Disclose
Ysushi Furuta MD, PhD, Abstract Co-Author: Nothing to Disclose

PURPOSE

Low iodine diet (LID) is an important preparation to enhance efficacy of radioiodine therapy for thyroid cancer. However, practice of stringent LID for longer duration could be complicated and boring. The aim of this study was to determine individual characteristics that are linked with failure of LID.

METHOD AND MATERIALS

We studied 38 patients with postsurgical papillary thyroid carcinoma who were to undergo rh-TSH aided remnant tissue ablation using 30mCi of I-131. Pathologic finding was either pT3/pT4 or pN1a/N1b in all. After counseling by a dietitian, LID was done from 8 days before to 2 days after administration of I-131. As a parameter of total body iodine, urinary iodine concentration normalized by urinary creatinin (UIC: μg/gCRE) was measured before start of LID (UICb) and on the day of I-131 ablation (UICp). Based on UICp, performance of LID was defined as successful (< 150) or unsuccessful ( ≥ 150). As possible factors for unsuccessful LID, we focused on age, gender, BMI, estimated GFR, residence, frequency of dinning out during LID period, given dose of l-T4, daily iodine consumption estimated by food frequency questionnaire, and UICb. Radioiodine uptake in the remnant tissue (RIU) was semi-quantitatively assessed using a gamma camera at 3 days after ingestion of I-131.

RESULTS

UICb and UICp ranged from 25 to 7840 and 19 to 1850(average: 723 and 181, respectively. 30 out of 38(79%) patients were assigned to successful LID while the remaining 8 (21%) was assigned to unsuccessful LID. There was a significant inverse correlation between UICp and RIU (r=-0.641). Also, there were significant difference in the RIU between patients with successful LID and those with unsuccessful LID(9.2 vs.5.8, p60 yrs.) and UICb (>400) were the significant factors associated with unsuccessful LID results.

CONCLUSION

Unsuccessful performance of LID was seen in about 20% of the patients. The older patients or patients with high UIC under routine diet have higher risk for unsuccessful LID performance. Those patients may require special consideration regarding LID protocol in depleting total body iodine for rh-TSH aided radioiodine ablation for thyroid cancer.

CLINICAL RELEVANCE/APPLICATION

For successful depletion of total body iodine for radioiodine ablation of remnant thyroid tissue, duration of stringency of LID may be adjusted for each patient according to age and UIC levels at routine dietary condition.

Cite This Abstract

Nakada, K, Tamura, M, Sakurai, M, Furuta, Y, The Effects of Age and Routine Dietary Iodine Consumption on Performance of Low Iodine Diet for rhTSH-aided Radioiodine Ablation for Papillary Thyroid Cancer.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14008394.html