_________________________________________________________________________ Thyroid Dysfunction
Thyrotropin Receptor Autoantibody (TRAb) Test The ATA guideline and the Mayo Clinic recommend TRAb testing as an option for establishing a definitive diagnosis when clinical findings are ambiguous and/or when Graves disease is suspected but thyroid function tests are normal [22; 25]. TRAb testing is particularly useful when radioactive iodine uptake testing is contraindicated, as in patients who are pregnant or breastfeeding. Other specific examples of TRAb test use in pregnant patients include determining the risk of neonatal thyrotoxicosis in a fetus of a patient with Graves disease, and the differential diagnosis of gestational thyrotoxicosis versus first trimester manifestation or recurrence of Graves disease [25]. TRAb testing is strongly recommended to guide medica- tion treatment decisions [22] . TREATMENT The three treatment options for hyperthyroidism are radiation, surgery, and thyroid-suppressing medication. Symptom relief is an important component of treatment. The choice of treat- ment depends upon the patient’s age, physical condition, and severity of disease [22; 23] . Radiation Radiation therapy using radioactive iodine (also referred to as radioiodine ablation) is considered the treatment of choice for most patients with hyperthyroidism. The effect of treatment with radioactive iodine is less rapid than either drug therapy or surgery; however, it is both safe and effective and does not require hospitalization [22]. Radioactive iodine is taken orally in doses of 4–10 mCi given on an empty stomach. The iodine is absorbed by the thyroid gland, causing it to shrink. Ideally, hyperthyroidism symptoms will subside within three to six months. The objectives of radioiodine ablation are to make the patient’s thyroid function normally or to disable it entirely, causing hypothyroidism, which can be easily treated with medication [22; 23] . It is advised that patients stop all antithyroid medications for one week prior to beginning treatment with radioactive iodine and for six weeks after therapy ends. Radiation precautions for body secretions should be used for three days after giving the dose; close personal contact with the patient should be avoided for one week. Ablation therapy is contraindicated during pregnancy or breastfeeding and is not recommended for use in children younger than 5 years of age; long-term antithyroid medications are preferred in this patient population [22]. Ablation therapy is the treatment preferred for the elderly or for patients con- sidered operative risks. It produces fast results with minimal adverse reactions [22; 23] .
DIAGNOSTIC TESTING According to a guideline from the American Thyroid Associa- tion (ATA), a thorough medical history and physical exam are the first steps in diagnosing hyperthyroidism. This should include measurement of pulse rate, blood pressure, respiratory rate, body weight, and an assessment of pulmonary, cardiac, and neuromuscular function. Thyroid size, symmetry, nodu- larity, and presence or absence of thyroid tenderness should also be assessed [22] . Symptoms and signs reported at this stage could have other explanations, particularly in the elderly; therefore, blood tests are necessary to establish a firm diagnosis. When hyperthyroid- ism is strongly suspected, diagnostic accuracy improves when both a serum TSH, free T 4 , and total T 3 are assessed at the time of initial evaluation. Again, a high level of T 4 and a low or absent amount of TSH in the serum indicate an overactive thyroid. In mild hyperthyroidism, free T 4 may be normal, with low or absent amounts of TSH in the serum, and only serum T 3 may be elevated. Biotin supplements can interfere with the results of TSH blood tests. Patients should be asked if they take biotin or multivitamin supplements and should be advised to avoid taking a supplement containing biotin for at least 12 hours prior to testing [22] . If the blood tests are positive for hyperthyroidism, further test- ing may be necessary to establish the etiology of the overactive thyroid. Most commonly, this includes a radioactive iodine uptake test, a thyrotropin receptor autoantibody (TRAb) test, and/or thyroid scan [22] . Radioactive Iodine Uptake Test The ATA guideline recommends that a radioactive iodine uptake test be performed when the diagnosis is in question (except during pregnancy). Prior to administering the test, medical therapy of any comorbid conditions should be opti- mized [22] . The radioactive iodine uptake test is used to assess the thyroid’s production of essential hormones and absorption of iodine. In this procedure, the patient is given a small oral dose of radioactive iodine. The iodine should collect in the thyroid gland, the amount of which will be measured after 2, 6, or 24 hours. A higher uptake of radioiodine indicates the thyroid gland is overproducing T 4 . This is an indicator of improperly functioning nodules or Graves disease [22] . Thyroid Scan The ATA guideline recommends that a thyroid scan be added in the presence of thyroid nodularity [22]. Thyroid scan may be conducted prior to biopsy and involves the injection of a radioactive isotope (usually technetium). An image of the thyroid gland is taken two hours after injection to determine whether the gland has nodules and if it is absorbing the iodine.
85
Book Code: ANCCTX2027
EliteLearning.com/Nursing
Powered by FlippingBook