WHAT IS THE THYROID GLAND?
Thyroid gland is an oval-shaped gland usually located in the lower part of the neck. The thyroid’s role is to produce thyroid hormones. They are then released into the bloodstream and transported to every cell inside the body. Thyroid hormones assist the body make energy, keeping warm, and help keep the heart, brain, muscles, and various organs operating as they should.
HOW DOES THE THYROID GLAND FUNCTION?
The primary thyroid hormone produced in the thyroid gland is thyroxine. It’s sometimes referred to as T4 due to its four Iodine atoms. T4 is converted to triiodothyronine (T3) to produce its effects by removing the iodine atom. This happens mostly in the liver and other tissues where T3 is active on a cellular level, for instance, within the brain.
The quantity of T4 produced by the thyroid gland is controlled by a different hormone produced by the pituitary gland in the middle of the brain. This hormone is called the thyroid-stimulating hormone (abbreviated TSH). The quantity of TSH that the pituitary gland releases into the bloodstream is dependent on the quantity of T4 that the pituitary gland sees.
If the pituitary sees very small amounts of T4, it creates more TSH to instruct that the thyroid gland is producing more T4. If the T4 in the bloodstream rises over a certain amount, the pituitary’s TSH production is stopped. The pituitary and thyroid work in various ways, similar to heating and thermostats. If the heater is turned off and gets cold, the thermostat reads the temperature and then turns to the furnace.
If the temperature rises to a certain amount, the thermostat recognizes this and shuts off the heater. The pituitary gland and the thyroid switch off like a heater and thermostat.
T4 and T3 both circulate
T4 and T3 both circulate nearly entirely bound by specific proteins for transport. If the level of these proteins changes, they can show variations in the amounts of T4, and the T3 bound to them is assessed. This is often the case in pregnancy and taking birth medication to control the birth. It is believed that “free” T4 or T3 is an unbound hormone that can get into the body and alter tissues.
TESTS
The tests for blood that measure the hormones in your body are easily available and widely utilized. However, not all can be useful in every situation. Tests to assess thyroid function include:
TSH TESTS
The best method to begin examining thyroid function is by measuring the TSH levels in the blood sample. The changes in TSH could be an “early warning system” that usually occurs before the amount of thyroid hormones within the body gets too high or low. The high level of TSH indicates that the thyroid isn’t producing sufficient thyroid hormone (primary hypothyroidism).
In contrast, a low TSH level suggests that the thyroid gland produces excessive thyroid hormone (hyperthyroidism). Sometimes the low TSH can result from an imbalance in the pituitary gland, which stops it from producing enough TSH to stimulate the thyroid (secondary hypothyroidism). In most healthy individuals, an average TSH level indicates that the thyroid is working well.
T4 TESTS
T4 is the primary thyroid hormone that circulates throughout the blood. The Total T4 is a measure of the bound and free hormone subject to alter when binding proteins differ (see the previous paragraph). A Free T4 measures the non-bound hormone and can enter and alter the body’s tissues. Tests to measure free T4 – or a free T4 (FT4) or the free T4 index (FTI) can more precisely show the function of the thyroid gland when tested using the TSH.
The presence of increased TSH and a low FT4 or FTI suggests the presence of primary hypothyroidism caused by thyroid gland disease. Low TSH and lower FT4 or FTI suggest hypothyroidism caused by an issue with the pituitary gland. A low TSH and an increase in FT4 or FTI are common in people who suffer from hyperthyroidism.
T3 TESTS
T3 tests are frequently beneficial for detecting hyperthyroidism or determining the extent of hyperthyroidism. Patients with hyperthyroidism can detect an increase in T3 levels. For some people with low TSH, just the T3 level is elevated, while it is not the case that FT4 and FTI can be normal.
T3 tests are rarely beneficial for patients suffering from hypothyroidism as it is the final test that can be abnormal. Patients may be hypothyroid if they have high TSH levels and the presence of low FT4 or FTI; however, they have normal T3.
FREE T3
The measurement of free T3 can be done by Chughtai lab. But it’s often insecure and thus not usually beneficial.
REVERSE T3
T3 reverse T3 is a biologically inactive protein structurally like T3. However, the iodine molecules are place in different places, rendering it inactive. The body naturally makes a small amount of reverse T3 but quickly degrades. In healthy, non-hospitalize individuals measuring reverse T3 cannot help determine if hypothyroidism is present or not and therefore is not clinically beneficial.
THYROID ANTIBODY TESTS
The immune system of the body guards us against foreign invaders like viruses and bacteria by killing these invaders by releasing substances known as antibodies that are produce by blood cells referred to as lymphocytes. For many people with hyperthyroidism or hypothyroidism, the lymphocytes react to the thyroid (thyroid autoimmunity) and produce antithyroid cell antibodies.
Two commonly used antibodies are the thyroid peroxidase and the thyroglobulin antibodies. Monitoring the levels of thyroid antibodies can aid in determining the root of thyroid issues. For instance, an antithyroid peroxidase test that is positive and anti-thyroglobulin antibodies found in patients who suffer from hypothyroidism can lead to a diagnosis of Hashimoto’s thyroiditis.
Although detecting antibodies can be helpful in the first diagnosis of hypothyroidism cause by autoimmune thyroiditis. Tracking the levels of these antibodies over time isn’t effective in determining the onset of hypothyroidism or response to treatment. TSH levels and FT4 are the two indicators we can use to learn about the thyroid’s function or levels.
Another antibody that could find to be positive in patients with hyperthyroidism could be an antibody called the stimulatory TSH receptor antibody (TSI). This antibody causes the thyroid to be hyperactive in the case of Graves ‘disease. If you suffer from Graves’s condition, your physician may request a thyrotropin test for antibodies (TSHR and TRAb) that detects both blocking and stimulating antibodies.
Monitoring the levels of antibodies in Graves’s patients can assist in assessing responses to treatment for hyperthyroidism. Determining the appropriate time to stop antithyroid medications, and evaluating the risk of passing antibodies onto the fetus in pregnancy.
THYROGLOBULIN
Thyroglobulin (Tg) is an enzyme produce from normal thyroid cells and thyroid cancer cells. It isn’t a measurement of thyroid function, and it cannot identify thyroid cancer if the thyroid gland remains in existence.
It is most commonly use for patients who have undergone surgery to treat thyroid cancer and track their progress following treatment. Tg is list in this guide of thyroid function tests to inform that although it is frequently use in certain situations and people. It is not an actual test of thyroid hormone function.
NON-BLOOD TESTS
RADIOACTIVE IODINE UPTAKE
Since T4 is a source of Iodine, the thyroid gland needs to draw an enormous amount of Iodine out of the bloodstream to produce the right quantity of T4. The thyroid has develop an active mechanism for this. You can monitor this activity by swallowing some radioactive Iodine. Radioactivity permits doctors to determine where the Iodine is take by determining how much radioactivity absorption in the thyroid gland (radioactive Iodine Uptake (RAIU).
Chughtai lab Report can establish whether the gland functions normally. A high RAIU is observe in people who have a hyperactive thyroid gland (hyperthyroidism). However, an extremely low RAIU can be observe when the thyroid gland has become inactive (hypothyroidism). Alongside the uptake of radioactive Iodine and thyroid scan. A thyroid scan could be take, which displays pictures of your thyroid. It also will reveal which areas that comprise the thyroid gland have absorbed the Iodine (see Thyroid Nodules brochure).
DRUGS THAT INTERFERE WITH THE THYROID FUNCTION TEST
There are a variety of medications that could influence thyroid function testing. Some common examples include:
* Estrogens used in birth control medications or during pregnancy can cause elevated levels of total T4 and T3. The reason for this is that estrogens raise the number of binding proteins. In these cases, it is best to request both TSH and free T4 for thyroid testing, usually within that normal level.
Biotin, a commonly consumed over-the-counter medication, may cause the results of several tests for thyroid function to be abnormal; however, they are normal in the blood. Shouldn’t take biotin for two days before the time the blood sample is take for thyroid function tests to avoid this problem.
Follow-up
If your blood test suggests the thyroid gland is in over-activity, the doctor could recommend the thyroid uptake test as well as an ultrasound.
If your scan results are not abnormal, the doctor will prescribe medication to control the thyroid’s activity. They will follow up with further thyroid function tests to ensure the medication is functioning. The tests will look for:
- Thyroid problems are structural. gland
- thyroid gland activity
- any tumours that could cause problems
The doctor could also recommend an ultrasound if they find an abnormality during the physical examination in your neck. If your results from the ultrasound aren’t as expected, the doctor could order an organ sample of the thyroid.
Thyroid cancer isn’t related to the source of hypothyroidism or hyperthyroidism. Remember that blood tests cannot be used to detect thyroid cancer.
