TRH Test In normal people TSH secretion from the pituitary can be increased by giving a shot containing TSH Releasing Hormone (e hormone released by the hypothalamus which tells the pituitary to produce TSH).
THBR tests should not be used as an independent measurement of thyroid status, but should be interpreted in association with a TT4 and/or TT3 measurement and used to produce free hormone estimates (FT4 or FT3 indexes).
149,153,154 Calculation of a FT4I using TBG only improves diagnostic accuracy compared with TT4 when the TT4 abnormality results from an abnormal concentration of TBG. In addition, the TT4/TBG index approach is not fully TBG independent, nor does it correct for non TBG-related binding protein abnormalities or for TBG molecules which have abnormal affinity.
The first free hormone tests developed in the 1960s were indexes, calculated from the product of the free hormone fraction from a dialysate multiplied by the TT4 measurement (made by PBI and later RIA).
Since TSH is normally low when the thyroid gland is functioning properly, the failure of TSH to rise when circulating thyroid hormones are low is an indication of impaired pituitary function.
Nothing in it is meant as a prescription or as medical advice. You should check with your physician before implementing any changes in your exercise or lifestyle habits, especially if you have physical problems or are taking medications of any kind.
Pregnant women should not have thyroid scans performed because the iodine can cause development troubles within the baby's thyroid gland. Two types of thyroid scans are available. A camera scan is performed most commonly which uses a gamma camera operating in a fixed position viewing the entire thyroid gland at once.
Knowing the weight of the thyroid gland allows more accurate radioactive treatment in patients who have Graves' disease. Thyroid Scans are used for the following reasons: Identifying nodules and determining if they are "hot" or "cold".
T3 Uptake does not measure the level of T3 or T4 in serum. Increased T3 uptake (decreased TBG) in euthyroid patients is seen in chronic liver disease, protein-losing states, and with use of the following drugs: androgens, barbiturates, bishydroxycourmarin, chlorpropamide, corticosteroids, danazol, d-thyroxine, penicillin, phenylbutazone, valproic acid, and androgens.
It is increased in hyperthyroidism and in euthyroid states characterized by increased TBG. Occasionally, hyperthyroidism will not be manifested by elevation of T4 (free or total but only by elevation of T3 (triiodothyronine).
The T4 reflects the amount of thyroxine in the blood. If the patient does not take any type of thyroid medication, this test is usually a good measure of thyroid function.
Excess TBG or low levels of TBG are found in some families as an hereditary trait. It causes no problem except falsely elevating or lowering the T4 level. These people are frequently misdiagnosed as being hyperthyroid or hypothyroid, but they have no thyroid problem and need no treatment.
For example, a low T4 level could mean a diseased thyroid gland. OR a non-functioning pituitary gland which is not stimulating the thyroid to produce T4. Since the pituitary gland would normally release TSH if the T4 is low, a high TSH level would confirm that the thyroid gland (not the pituitary gland) is responsible.