Do You Have a Low Thyroid Causing Problems Losing Weight?
Thyroid weight gain is due to low thyroid gland function and is a common cause of difficulty loosing weight. Up to 300 million people suffer from an underactive thyroid all over the world. In the US 4.6% of the population (5 out of every 100 people suffers from a low thyroid , and mounting scientific research links slow thyroid levels to stubborn weight loss resistance and countless other serious health conditions,
A butterfly-shaped gland located in the center of the neck, your thyroid produces two vital metabolism-regulating hormones: triiodothyronine (T3) and thyroxine (T4), both controlled by your pituitary gland through the thyroid-stimulating hormone (TSH).
Low Thyroid Function and Weight Gain in Women (…and men)
Ten times more women than men have an under active thyroid; it typically starts between the age of 40 to 50, along with the other hormonal changes occurring at this stage in women’s life. More and more women start experiencing the three most common hypothyroid symptoms (weight gain, fatigue/depression and skin changes). The most common problem is to differentiate these symptoms which are shared by many other diseases from the true hypothyroid state. When all three of the symptoms occur together, it’s easy, however, more often than not, only 1 or 2 symptoms may be present at a time. For borderline hypothyroid cases often none of the symptoms are present except for the inability to lose weight.
Symptoms Associated with Low Thyroid Function
Here are the many symptoms associated with a low thryoid gland function. Note the significant overlap with other medical problems making the diagnosis often difficult.
What Blood Tests are Used to Assess Thyroid Function?
Thyroid weight gain is evaluated usually by the TSH test. TSH is the key hormone for diagnosing hyperthyroidism and hypothyroidism. If results of the TSH test are abnormal, one or more additional tests are needed to help determine the cause of the problem.
Thyroid Weight Gain and TSH Test
This blood test is the most sensitive test of thyroid function available. The TSH test can detect TSH blood levels as low as 0.01 milli-international units per liter (mIU/L). The normal range for TSH is between 0.3 and 3 mIU/L, although the range varies from one laboratory to another. Between 3 to 3.8 is borderline and 3.9 or higher is indicative of low thryoid function.
The TSH test is based on the way TSH and thyroid hormones work together. Normally, the pituitary boosts TSH production when thyroid hormone levels in the blood are low. The thyroid responds by making more hormone. Then, when the body has enough thyroid hormone circulating in the blood, TSH output drops. The cycle repeats continuously to maintain a healthy level of thyroid hormone in the body. The TSH test measures the amount of TSH being secreted by the pituitary.
In people whose thyroid produces too much thyroid hormone, the pituitary shuts down TSH production, leading to low or even undetectable TSH levels in the blood. An abnormally low TSH level suggests hyperthyroidism.
In people whose thyroid is not functioning normally and produces too little thyroid hormone, the thyroid cannot respond normally to TSH by producing thyroid hormone. As a result, the pituitary keeps making TSH, trying to get the thyroid to respond. An abnormally high TSH level suggests hypothyroidism.
Occasionally, however, a low TSH level can indicate a type of hypothyroidism called secondary hypothyroidism. Instead of a problem with the thyroid gland, this type of hypothyroidism is caused by an abnormality in the pituitary that prevents it from making enough TSH to stimulate thyroid hormone production.
Very rarely, hyperthyroidism can result from a problem with the pituitary rather than the thyroid. Noncancerous, or benign, pituitary tumors may overproduce TSH and cause thyroid hormone levels to rise. However, such tumors are extremely rare. The usual cause of a high TSH level is an underfunctioning thyroid gland or inadequate dosage of thyroid hormone medication in patients taking replacement hormone.
T4 Tests in Low and High Thyroid Conditions
T4 is the principal thyroid hormone and exists in two forms-T4 that is bound to proteins in the blood and kept in reserve until the body needs it, and a small amount of unbound or “free” T4 (FT4), which is the active form of the hormone and is available to body tissues. The normal range for total T4-bound and free together-is usually about 4.5 to 12.6 micrograms per deciliter (µg/dL), although the range varies from one laboratory to another. The normal FT4 range is about 0.7 to 1.8 nanograms per deciliter (ng/dL).
Elevated total T4 or FT4 suggests hyperthyroidism, and low total T4 or FT4 suggests hypothyroidism. Sometimes total T4 levels are abnormal because the protein-bound T4 is abnormally high or low due to elevated or low concentrations of the protein that binds T4. Therefore, FT4 must be calculated separately.
Measuring FT4 directly requires complicated laboratory procedures, so FT4 is usually estimated based on the ratio of binding protein to total T4. Normal FT4 levels, when the total T4 is high or low, indicate the issue is the binding protein, not the thyroid. For example, pregnancy or the use of oral contraceptives increases levels of binding protein in the blood. In this case, the total T4 will be high due to the binding protein but the person does not have hyperthyroidism. Severe illness or the use of corticosteroids-a class of medications that treat asthma, arthritis, and skin conditions, among other health problems-can decrease binding protein levels. The total T4 measurement will be low as a consequence, but the person does not have hypothyroidism. In either case-having high binding protein or having low binding protein-the FT4 will be normal and the person has normal thyroid function-also called euthyroid.
T3 Not Good Test for Thyroid Weight Gain
Only about 20 percent of the T3 circulating in the blood comes from the thyroid gland, while all of the circulating T4 comes from the thyroid. The remaining 80 percent of circulating T3 comes from various cells all over the body where T4 is converted to T3. T3 is far more active than T4 and, like T4, exists in both bound and free states. In some cases of hyperthyroidism, FT4 is normal but free T3 (FT3) is elevated, so measuring both forms is useful if hyperthyroidism is suspected. The normal FT3 range is about 0.2 to 0.5 ng/dL. The T3 test is not useful in diagnosing hypothyroidism because levels are not reduced until the hypothyroidism is severe.
Imaging Tests in Thyroid Disease
A physician may use one or a combination of imaging tests, such as an ultrasound of the thyroid, a computerized tomography (CT) scan, or nuclear medicine tests, to diagnose and find the cause of thyroid disorders. Thyroid imaging is reviewed at the National Institutes of Health report on thyroid disease.