Comparison Between The Effect Of One-Week Against Two-Week Iodine Restricted Diet On The Post Radioiodine Therapy Outcome Among Hyperthyroidism Patients In A Regional Nuclear Medicine Referral Centre
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Date
2016
Authors
Zainal, Ahmad Zaid
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Introduction: Therapy using radioactive Iodine-131 is an established method of treatment for thyroid diseases including hyperthyroidism related benign disorders as well as thyroid cancers. Pre-treatment dietary restriction to induce a state of iodine deficiency is considered important and may influence the radioiodine therapy outcome. Although there are no specific guidelines of dietary preparation for benign thyroid disorders, the current practice in most nuclear medicine centres in Malaysia is to advice one-week dietary restriction for hyperthyroidism patients as compared to two-week duration for thyroid cancer patients.
Objective: The aim of this study is to evaluate the effect of one-week against two-week iodine restricted diet on the post radioiodine therapy levels of serum thyroid stimulating hormone (TSH) and free thyroxine (T4) levels as well as the treatment outcome.
Methods: Hyperthyroidism patients referred for first radioiodine therapy were randomised into two groups according to one-week or two-week dietary restriction. There were 83 patients (n=44 in one-week dietary restriction group, n=39 in two-week group). Pre-therapy urinary iodine test was done to document compliance towards the dietary restriction. Favourable therapy outcome includes euthyroid or hypothyroidism at 9 months post therapy. Demographic and clinical data were collected and analysed.
Results: Majority of the patients were females with mean age of 42 years old and had goitre clinically. At 9th month follow-up, majority of patients (83%) achieved favourable thyroid status. No significant statistical association was found between the duration of dietary restriction with mean free T4 (p=0.057) and serum TSH (p=0.746) levels as well as therapy outcome (p=0.294). However, male patients were 6.22 times more likely to develop unfavourable post therapy outcome compared to female patients and an increasing level of pre-treatment urinary iodine was associated with increased likelihood of developing unfavourable post therapy outcome.
Conclusion: There is no significant difference between the effects of one-week against two-week iodine restricted diet on the post radioiodine therapy outcome. Although generally a period of one-week iodine restriction appears to be adequate for the preparation of hyperthyroidism patients, efforts to ensure adequate compliance and stringency should be advocated as these may possibly influence the efficacy of dietary restriction and radioiodine therapy. Future studies with larger sample size and covering other contributing factors are recommended.
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Keywords
Therapy using radioactive Iodine , treatment for thyroid diseases.