放射性碘摄取

定义

放射性碘摄取 (RAIU) tests thyroid function. It measures how much radioactive iodine is taken up by your thyroid gland in a certain time period.

一个类似的测试是 甲状腺扫描. The 2 tests are commonly performed together, but they can be done separately.

选择的名字

Thyroid uptake; Iodine uptake test; RAIU

如何执行测试

测试是这样完成的:

• You are given a pill that contains a tiny amount of radioactive iodine. After swallowing it, you wait as the iodine collects in the thyroid.
• The first uptake is usually done 4 to 6 hours after you take the iodine pill. Another uptake is usually done 24 hours later. During the uptake, you lie on your back on a table. A device called a gamma probe is moved back and forth over the area of your neck where the thyroid gland is located.
• The probe detects the location and intensity of the rays given off by the radioactive material. A computer displays how much of the tracer is taken up by the thyroid gland.

该测试耗时不到30分钟, but you will need to come back twice to have the scans performed.

如何准备考试

Follow instructions about not eating before the test. You may be told not to eat after midnight the night before your test.

Your health care provider will tell you if you need to stop taking medicines before the test that may affect your test results. DO NOT stop taking any medicine without first talking to your provider.

如果你有以下情况，请告诉你的十大赌博平台排行榜:

• Diarrhea (may decrease absorption of the radioactive iodine)
• Had recent CT scans using intravenous or oral iodine-based contrast (within the past 2 weeks)
• Too little or too much iodine in your diet

考试的感觉如何

没有不适. You can eat beginning about 1 to 2 hours after swallowing the radioactive iodine. You can go back to a normal diet after the test.

为什么要进行测试

This test is done to check thyroid function. It is often done when blood tests of thyroid function show that you may have an overactive thyroid gland.

正常的结果

These are normal results at 6 and 24 hours after swallowing the radioactive iodine:

• 6小时:3%到16%
• 24小时:8%至25%

Some testing centers measure only at 24 hours. Values may vary depending on the amount of iodine in your diet. Normal value ranges may vary slightly among different labs. Talk to your provider about the meaning of your specific test results.

异常结果意味着什么

Higher-than-normal uptake may be due to an overactive thyroid gland. 最常见的原因是 格雷夫斯病.

Other conditions can cause some areas of higher-than-normal uptake in the thyroid gland. 这些包括:

• An enlarged thyroid gland that contains nodules producing too much thyroid hormone (中毒性结节性甲状腺肿)
• A single thyroid nodule that is producing too much thyroid hormone (toxic adenoma)

These conditions often result in normal uptake, but the uptake is concentrated into a few (hot) areas while the rest of the thyroid gland does not take up any iodine (cold areas). This can only be determined if the scan is done along with the uptake test.

低于正常摄取量可能是由于:

• 人为的甲状腺机能亢进 (taking too much thyroid hormone medicine or supplements)
• 碘过量
• 亚急性甲状腺炎 (swelling or inflammation of the thyroid gland)
• 无声的(或无痛的)甲状腺炎
• Amiodarone (medicine to treat some kinds of heart disease)

风险

所有的辐射都可能有副作用. The amount of radiation in this test is very small, and there have been no documented side effects.

Women who are pregnant or breastfeeding should not have this test.

Talk to your provider if you have concerns about this test.

注意事项

The radioactive iodine leaves your body through your urine. You should not need to take special precautions, 如小便后冲洗两次, 测试后24到48小时. Ask your provider or the radiology/nuclear medicine team performing the scan about taking precautions.

参考文献

Guber HA, Oprea M, Rusell YX. 内分泌功能评价. 见:McPherson RA, Pincus MR，编辑. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24日艾德. Philadelphia, PA: Elsevier; 2022:chap 25.

梅特勒FA，吉伯特MJ. Thyroid, parathyroid, and salivary glands. 见:梅特勒FA，吉伯特MJ，编. Essentials of Nuclear Medicine and Molecular Imaging. 7日艾德. Philadelphia, PA: Elsevier; 2019:chap 4.

萨尔瓦多D，科恩R，科普PA，拉森PR. Thyroid pathophysiology and diagnostic evaluation. In: Melmed S, Auchus RJ, Goldfine AB, Koenig RJ, Rosen CJ, eds. 威廉斯内分泌学教科书. 14日艾德. Philadelphia, PA: Elsevier; 2020:chap 11.

Weiss RE, Refetoff S. 甲状腺功能检查. In: Jameson JL, De Groot LJ, de Kretser DM, et al, eds. 内分泌学:成人和儿童. 7日艾德. Philadelphia, PA: Elsevier Saunders; 2016:chap 78.