Pituitary Hypothyroidism And Hormone Deficiencies

How does radioactive iodine work?

The thyroid gland absorbs iodine from the blood. When radioactive iodine enters your thyroid, it slowly shrinks the gland over a period of weeks or months.

The treatment is safe, simple, convenient, and inexpensive. It is usually given only once, rarely causes any pain or swelling, and does not increase the risk of cancer. However, it must be avoided during pregnancy or nursing, and patients should not become pregnant for at least six months after treatment.

When is radioactive iodine used?

Radioactive iodine is the most common treatment for hyperthyroidism. It does not require hospitalization. About 90% of patients need only one treatment. They usually start getting better in three to six weeks, and most are cured within six months.

This treatment may also be used after surgery for certain thyroid cancers. Radioactive iodine dissolves any cancerous tissue that could not be removed by surgery. The dose of radioactive iodine is larger in this case, and patients usually stay in the hospital for a day or two.

What can be expected with radioactive iodine treatment for hyperthyroidism?

• It is usually given in liquid form or as a capsule. The dose can range from 4 to 29 millicuries.
• It is tasteless.
• There are almost never any side effects. In some rare cases, there can be an inflammation of the thyroid gland causing a sore throat and discomfort.
• Radioactive iodine not taken up by the thyroid gland is excreted in urine and saliva. There is no evidence that the small amount of I¹³¹ excreted in the urine and saliva is harmful. Nonetheless, prudent nuclear medicine experts have recommended a wide variety of precautions. While these recommendations are sometimes confusing and inconsistent, it may be appropriate to take a few simple measures to avoid unnecessary exposure of infants and children to I¹³¹. Treated patients should rinse out their glasses or cups and eating utensils immediately after drinking and eating. The toilet should be flushed immediately after use, and the rim of the bowl should be wiped dry, if necessary.
• It is advisable to drink two to three extra glasses of water a day during the four- to seven- day period following radioactive treatment so that radioactive material will not collect in the bladder for a long period of time.
• Because radioactive iodine passes into breast milk, breast feeding mothers are asked to wean their babies before treatment.
• It typically takes six weeks before thyroid hormone production is noticeably reduced. The average length of time for the thyroid hormone levels to become normal is about three to four months. If thyroid levels are not considerably reduced six months after treatment, the doctor might suggest repeating the treatment. Ninety percent of the time only one treatment is required; however, it might take as many as three attempts. The patient could be advised to take beta-blocking drugs and other medications the doctor believes are necessary until normal thyroid hormone production is restored.
• Many patients treated with radioactive iodine become hypothyroid. This may happen within weeks, months, or years of treatment. Therefore, patients should be aware of the signs and symptoms of hypothyroidism, and their physicians should monitor their thyroid hormone levels regularly. When the patient becomes hypothyroid, thyroid hormone replacement begins and continues for life-one pill a day.

If you have thyroid disease, your doctor can discuss which treatment is right for you. The two basic goals for treating thyroid disease are to return thyroid hormone levels to normal and to remove potentially cancerous lumps. Treatments include radioactive iodine, antithyroid drugs, beta-blocking drugs, thyroid hormone pills, and surgery. There are several types of treatment:

• Radioactive iodine is used to shrink a thyroid gland that has become enlarged or is producing too much hormone. It may be used on patients with hyperthyroidism, a goiter, or some cases of cancer.
• Surgery is normally used to remove a cancer and may also be used to remove a large goiter.
• Thyroid hormone pills are a common treatment for hypothyroidism, for patients with a goiter, and for patients who have had thyroid surgery. The pills provide the body with the right amount of thyroid hormone.
• Anithyroid drugs and beta-blocking drugs are used to treat hyperthyroid patients.

How is thyroid disease discovered?

As with any disease, it is important that you watch for the early warning signs. However, only your doctor can tell for sure whether or not you have thyroid disease. He or she can measure the amount of thyroid hormones in your blood, as well as look at the structure and function of your thyroid gland. If a nodule is found, your doctor can test whether or not it is cancerous.

What are the signs and symptoms of thyroid disease?

When your doctor examines you for thyroid disease, he or she should first ask about your symptoms and then check for physical signs. Your doctor will ask questions about your memory, emotions, or menstrual flow, and then check your heart rate, muscles, skin, and thyroid gland.

Which blood tests will my doctor use?

After a physical examination, your doctor may examine certain hormone levels in your blood. The most common tests check the levels of thyroid hormones (T₄ and T₃) and thyroid stimulating hormone (TSH). Your doctor may also perform a test with an injection of thyrotropin releasing hormone (TRH). If your doctor suspects Hashimoto’s thyroiditis or Graves’ disease, he or she will probably test you for antithyroid antibodies or thyroid stimulating antibodies.

What does the radioactive iodine uptake show?

Iodine is an important building-block for thyroid hormones. Your doctor may give you a small amount of radioactive iodine and then measure the amount absorbed by the thyroid gland. If the thyroid absorbs a lot of this iodine, you may be hyperthyroid. Low iodine uptake may signal hypothyroidism or thyroiditis.

Why is the structure of my thyroid important?

Examining the structure of your thyroid gland and the surrounding area tells your doctor about a lump (nodule) which may be cancerous or enlargement of the thyroid (goiter).

Which tests look at the structure of my thyroid?

• A thyroid image (or scan) shows the size, shape, and function of the gland. It uses a radioactive chemical, usually iodine or technetium, which the thyroid absorbs from the blood. A special camera then creates a picture, showing how much chemical was absorbed by each part of the gland. The test shows the size of the thyroid and tells whether lumps are hot (usually benign) or cold (either benign or malignant). The scan is frequently done at the same time as the radioactive iodine uptake.
• In needle aspiration biopsy, a small needle is inserted into the nodule in an effort to suck out (aspirate) cells. If the nodule is a fluid-filled cyst, the needle often removes some or all of the fluid. If the nodule is solid, several small samples are removed for examination under the microscope. Over 90% of the time, this testing tells the doctor whether the nodule is cancerous or not.
• Ultrasound uses high-pitch sound waves to find out whether a nodule is solid or filled with fluid. About 10% of nodules are fluid-filled cysts, and they are usually not cancerous. Ultrasound may also detect other nodules that are not easily felt by the doctor. The presence of multiple nodules reduces the likelihood of cancer.