本研究目的為探討甲狀腺癌術後病人採低碘飲食的持續時間對尿碘濃度之影響。依據PICO (Population-Intervention-Comparison-Outcome)方式設立臨床問題，P為甲狀腺癌行甲狀腺術後預計行放射碘治療病人；I為小於等於二週低碘飲食；C為大於二週低碘飲食；O為尿碘、碘/肌酐(I/ Cr)比值變化。以系統性文獻回顧法，搜尋資料庫包括華藝線上圖書館、PubMed、The Cochrane Library、Embase資料庫，使用關鍵字包含甲狀腺切除手術(Thyroidectomy)、放射線碘治療(Radioactive iodine treatment: RIT)、低碘飲食(Low iodine diet: LID)及尿硪濃度(Urine iodine concentration)，最後選擇5篇符合主題之文獻，分別為二篇世代性研究、二篇隨機控制試驗、一篇系統性文獻回顧，依照Oxford CEBM建議等級，證據等級1-3，統整結果顯示放射碘治療前進行低碘飲食1~2週，即可達到治療成效，與限碘飲食無差異，並建議未來須進行放射線碘治療患者,進行前持續低碘飲食1-2週即可。

The purpose of this study was to investigate the effect of the duration of a low iodine diet on urinary iodine concentration in patients with thyroid cancer after thyroidectomy. According to the PICO (Population- Intervention-Comparison-Outcome) method to establish clinical problems, Population is patients with thyroid cancer who have completed thyroidectomy and will undergo radioiodine treatment; Intervention is less than or equal to two weeks of low iodine diet; Comparison is more than two weeks of low iodine diet; Outcome is the urine iodine and iodine/creatinine (I/Cr) ratio. A systematic review was conducted. Electronic databases including, Cochrane Library, EBSCO, PubMed and Airiti library were retrieved for relevant articles. Finally, 5 articles that match the inclusion criteria were selected including 2 cohort studies, 2 randomized controlled trials (RCT), and 1 systematic review (SR). Based on the five studies, it is validated that using low-iodine diet 1 to 2 weeks before radioiodine treatment can achieve the optimal therapeutic effect with the evidence on level 1 to level 3 according to 2011 OCEBM. As a result, it is recommended that patients who receive radiation iodine should be educated for low-iodine diet for 1~2 weeks before the treatment.