Iodine Uptake Scan A means of measuring thyroid function is to measure how much iodine is taken up by the thyroid gland (RAI uptake). Remember, cells of the thyroid normally absorb iodine from our blood stream (obtained from foods we eat) and use it to make thyroid hormone (described on our thyroid function page ).
Both of the scans above show normal sized thyroid glands, but the one on the left has a ". HOT " nodule in the lower aspect of the right lobe, while the scan on the right has a " COLD " nodule in the lower aspect of the left lobe (outlined in red and yellow).
It has also been found that thyroid nodules that concentrate iodine are rarely cancerous; this is not true if the scan is done with technetium. Therefore, all scans are now done with radioactive iodine.
It also may help if your child looks away when the needle is being inserted into the skin. If You Have Questions If you have questions about the T4 test, contact your doctor.
Of course, patients who are taking thyroid medication will not take up as much iodine in their thyroid gland because their own thyroid gland is turned off and is not functioning.
If the T4 level is low and TSH is not elevated, the pituitary gland is more likely to be the cause for the hypothyroidism. Of course, this would drastically effect the treatment since the pituitary gland also regulates the body's other glands (adrenals, ovaries, and testicles) as well as controlling growth in children and normal.
Double-check the diagnosis of an underactive thyroid gland in a newborn (congenital hypothyroidism). How To Prepare Tell your doctor if you have had any tests in which you were given radioactive materials or had X-rays that used iodine dye within the last 4 to 6 weeks.
Measurement of Serum Thyroid Hormones: T3 by RIA. As stated on our thyroid hormone production page, thyroxine (T4) represents 80 of the thyroid hormone produced by the normal gland and generally represents the overall function of the gland.
Therefore, it is usually done at the same time that the iodine uptake test is performed. Although other isotopes, such as technetium, will be concentrated by the thyroid gland; these isotopes will not measure iodine uptake which is what we really want to know because the production of thyroid hormone is dependent upon absorbing iodine.
Free thyroxine (free T4) tests are used to help evaluate thyroid function and diagnose thyroid diseases, including hyperthyroidism and hypothyroidism.
Measurement of Pituitary Production of TSH. Pituitary production of TSH is measured by a method referred to as IRMA (immunoradiometric assay). Normally, low levels (less than 5 units) of TSH are sufficient to keep the normal thyroid gland functioning properly.
For example, an overactive thyroid, called hyperthyroidism, is typically associated with symptoms like weight loss, a fast heart rate, and sweating. An underactive thyroid, called hypothyroidism, may cause symptoms such as weight gain, fatigue, and feeling cold.
A needle is inserted into a vein (usually in the arm inside of the elbow or on the back of the hand) and blood is withdrawn and collected in a vial or syringe.