Thyroxine

Before the Test There are no preparations that need to be done ahead of time with a free T4 test, but you do need to tell your healthcare provider about any medications, vitamins, or herbs you are taking ahead of time, as these can interfere with the results of the test. Most healthcare providers will recommend having your blood drawn before you take any medications, if possible. If you’re suffering from an illness such as a cold, your healthcare provider may also choose to postpone the blood draw until you’ve recovered. The test itself should only take a few minutes, and the results should be available a few days after your healthcare provider sends your blood vial off to the lab to be examined. What to Wear Remember to wear a shirt that can be easily rolled up, or a sweatshirt with a t-shirt underneath so that you can remove it for the blood draw. It’s important for the technician performing the blood draw to be able to access your arm to find the best vein from which to take blood with minimal discomfort to you. Food and Drink Unless specified by your healthcare provider, hold off on any vitamins or medications until after your free T4 test. Supplements containing biotin should be ceased four days before the test. Make sure you eat a healthy meal or snack an hour or two before your free T4 test to prevent getting dizzy or lightheaded during the blood draw. Interpreting Results Once your healthcare provider sends the blood draw off to the lab for analysis, the results sh...

Allergies Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully. Pediatric Appropriate studies performed to date have not demonstrated pediatric-specific problems that would limit the usefulness of levothyroxine in children. However, your child's doctor will check your child closely for heart problems during the first 2 weeks of treatment. Geriatric Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of levothyroxine in the elderly. However, elderly patients are more likely to have age-related heart or blood vessel problems, which may require caution and an adjustment in the dose for patients receiving levothyroxine. Breastfeeding Studies in women suggest that this medication poses minimal risk to the infant when used during breastfeeding. Drug Interactions Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medici...

Check with your doctor immediately if any of the following side effects occur: Less common • Chest pain, discomfort, or tightness • decreased urine output • difficult or labored breathing • difficulty with swallowing • dilated neck veins • extreme fatigue • fainting • fast, slow, irregular, pounding, or racing heartbeat or pulse • fever • heat intolerance • hives or welts, skin itching, rash, or redness • irregular breathing • irritability • menstrual changes • nausea • pain or discomfort in the arms, jaw, back, or neck • sweating • swelling of the eyes, face, lips, throat, or tongue • tremors Rare • Blurred or double vision • dizziness • eye pain • lack or slowing of normal growth in children • limp or walk favoring one leg • pain in the hip or knee • seizures • severe headache Get emergency help immediately if any of the following symptoms of overdose occur: Symptoms of overdose • Change in consciousness • cold, clammy skin • confusion • disorientation • fast or weak pulse • lightheadedness • loss of consciousness • sudden headache • sudden loss of coordination • sudden slurring of speech Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if ...

Overview What is a T4 (thyroxine) test? A T4 (thyroxine) test helps diagnose Your Thyroxine, also known as T4, is the major type of hormone your thyroid releases. Too much or too little T4 can indicate thyroid disease. Healthcare providers test T4 levels using blood tests. Thyroxine (T4) comes in two forms: • Bound T4: This form attaches to proteins, which prevents it from entering your body’s tissues. • Free T4: This form “freely” enters your body’s tissues where it’s needed. Because of this, there are a few different tests that measure T4 levels. A blood test that measures both free and bound T4 is called a total T4 test. Other blood tests measure just free T4. Healthcare providers most often use a free T4 test to assess Your healthcare provider will most likely also order a A TSH test is the best way to initially assess thyroid function. In fact, T4 tests more accurately reflect thyroid function when combined with a TSH test. Measuring T4 levels might not be necessary in all thyroid conditions. Other names for a T4 test include: • Free thyroxine. • Total T4 concentration. • Thyroxine screen. • Free T4 concentration. • Free T4 index (FTI). What is thyroxine (T4) and what does it do? Thyroxine, also known as T4 and tetraiodothyronine, is the main hormone your thyroid gland releases into your bloodstream. Your thyroid also releases small amounts of triiodothyronine (T3). T4 and T3 work together and are commonly referred to as “thyroid hormone.” The T4 your thyroid releases...

What is thyroid hormone replacement therapy? Thyroid hormone therapy is the use of manmade thyroid hormones to raise abnormally low levels of natural thyroid hormones in the body. Thyroid hormone is usually given in pill form and is often used to treat an underactive thyroid that is secreting little or no thyroid hormones. The most commonly prescribed thyroid hormone replacement is pure synthetic thyroxine (T4). Who needs thyroid hormone replacement therapy? Thyroid hormone therapy is generally prescribed when your thyroid is not making enough thyroid hormone naturally. This is a condition referred to as hypothyroidism. Other reasons for using thyroid hormone therapy may rarely include: • To control the growth of the enlarged thyroid gland (also called goiter) • To control the growth of nodules on the thyroid gland • Treatment after the removal of the thyroid for benign or malignant disease • After treatment of hyperthyroidism by radioactive iodine ablation How is thyroid hormone replacement therapy dosage determined? Healthcare providers do careful blood testing to find the proper dose of hormone replacement therapy for each person.The blood tests reveal levels of thyroid hormones in the blood, as well as thyroid-stimulating hormone (TSH)released by the pituitary gland. The pituitary gland plays an integral role in the functioning of the thyroid gland. It controls how much thyroid hormone is released by making TSH that "stimulates" the thyroid. Increased levels of TSH may...

THYROID HORMONE TREATMENT Thyroid hormone is used in two situations: • to replace the function of a thyroid gland that is underactive or has been surgically removed (“ replacement therapy“) and • to prevent further growth of thyroid tissue (“ suppression therapy“). Suppression therapy is used primarily in patients with thyroid cancer to prevent recurrence or progression of their cancer. DEFINITION, THERAPY & TREATMENT THYROID HORMONE REPLACEMENT THERAPY Many people have a thyroid gland that cannot make enough thyroid hormone for the body’s needs. This is called Hypothyroidism and is most commonly caused by an under functioning thyroid gland due to Hashimoto’s disease. Other causes of hypothyroidism are: surgical removal, destruction of thyroid gland from radiation treatment, or a nonfunctioning pituitary gland (see Hypothyroidism Brochure). Hypothyroidism is the most common reason for needing thyroid hormone replacement. Thyroid hormone is necessary for the health of all the cells in your body. Taking thyroid hormone is different from most medications, because its job is to replace a hormone that is missing. The goal of thyroid hormone treatment is to closely replicate normal thyroid functioning. Thyroid hormone is available as levothyroxine, which is biologically equivalent to your own thyroid hormone, thyroxine ( T4). It is most commonly prescribed in tablet form but is now also available in gel capsule or liquid forms. The only safety concerns about taking thyroid hormo...