Misc Flashcards
Which is the more active form of thyroid hormone?
T3 or T4
T3
Most of the T4 and T3 in the bloodstream is carried bound to a _______ called __________
protein, thyroxine-binding globulin.
To produce thyroid hormones, the thyroid gland needs ___________
iodine
A lab measure of T4 measures
Total T4 measures the bound and free hormone and can change when binding proteins differ
Lab measure of TSH measures
A high TSH level indicates that the thyroid gland is not making enough thyroid hormone (primary hypothyroidism). The opposite situation, in which the TSH level is low, usually indicates that the thyroid is producing too much thyroid hormone (hyperthyroidism). Occasionally, a low TSH may result from an abnormality in the pituitary gland, which prevents it from making enough TSH to stimulate the thyroid (secondary hypothyroidism). In most healthy individuals, a normal TSH value means that the thyroid is functioning properly.
Free T4 measures
A Free T4 measures what is not bound and able to enter and affect the body tissues.
T3 Tests measure:
T3 tests are often useful to diagnosis hyperthyroidism or to determine the severity of the hyperthyroidism. Patients who are hyperthyroid will have an elevated T3 level. In some individuals with a low TSH, only the T3 is elevated and the FT4 or FTI is normal. T3 testing rarely is helpful in the hypothyroid patient, since it is the last test to become abnormal. Patients can be severely hypothyroid with a high TSH and low FT4 or FTI, but have a normal T3.
Free T3 test measures
Unbound hormone in blood. (unattached to protein)
It is ordered primarily to help diagnose hyperthyroidism and may be ordered to help monitor treatment of a person with a known thyroid disorder
Reverse T3 measures
Reverse T3 is a biologically inactive protein that is structurally very similar to T3, but the iodine atoms are placed in different locations, which makes it inactive. Some reverse T3 is produced normally in the body, but is then rapidly degraded.
If suspecting Hashimotos, these antibody tests may be ordered:
Two common antibodies are thyroid peroxidase antibody and thyroglobulin antibody. Measuring levels of thyroid antibodies may help diagnose the cause of the thyroid problem. For example, positive anti-thyroid peroxidase and/or anti-thyroglobulin antibodies in a patient with hypothyroidism result in a diagnosis of Hashimoto’s thyroiditis.
