|
The radioactive iodine uptake test, or RAIU test, is a type of scan used in the diagnosis of thyroid problems, particularly hyperthyroidism. It is entirely different from radioactive iodine therapy (RAI therapy), which uses much higher doses to destroy cancerous cells. The RAIU test is also used as a follow up to RAI therapy to verify that no thyroid cells survived, which could still be cancerous.〔() ThyCa: Thyroid Cancer Survivors' Association, Inc.,Radioactive Iodine (RAI).〕 The patient swallows radioactive iodine in the form of capsule or fluid, and its absorption by the thyroid is studied after 4–6 hours and after 24 hours with the aid of a scintillation counter. The dose is typically 0.15–0.37 MBq (4–10 μCi) of 131I sodium iodide, or 3.7–7.4 MBq (100–200 μCi) of 123I sodium iodide. The normal uptake is between 15 and 25 percent, but this may be forced down if, in the meantime, the patient has eaten foods high in iodine, such as dairy products and seafood.〔M. Sara Rosenthal. ''The Thyroid Sourcebook.'' McGraw-Hill, 2008. Page 140.〕 Low uptake suggests thyroiditis, high uptake suggests Graves' disease, and unevenness in uptake suggests the presence of a nodule.〔(WebMD article ) on RAIU test.〕 I-123 has a shorter half life than I-131 (a half day vs. 8.1 days), so use of I-123 exposes the body to less radiation, but at the expense of less time to evaluate delayed scan images. Also, I-123 emits gamma radiation, while I-131 emits gamma and beta radiation. ==Contraindications== The test is inappropriate for patients who are pregnant or breastfeeding.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Radioactive iodine uptake test」の詳細全文を読む スポンサード リンク
|