Thyroxine (T4) is one of the hormones produced by the thyroid gland that helps regulate the adrenal system, and plays a role in energy, normal growth and development, ability to maintain a healthy weight, and in mood stability. The other hormone produced by the thyroid gland is T3 or triiodothyronine. Both of these hormones get produced when the pituitary gland creates thyroid-stimulating hormone (TSH). Either of these hormones may be excessive (hyperthyroidism) or below normal levels (hypothyroidism) and this can have serious effects on the body.
Thyroid hormones are essential. An inadequate supply in infants and children, for instance, can retard growth and cause mental retardation. In many countries, thyroid levels are checked on infants to make certain they have a functioning thyroid gland. In adults with low amounts, a number of the body’s systems may not work as well as they should. The body’s metabolism may be depressed, leading to easy weight gain, and even things like poor respiration and cardiac output.
Thyroxine’s effect on mood and mental illness is beginning to be studied extensively. There is increasing evidence that people with conditions like major depression and bipolar disorder may have low levels of thyroid function. There is also some evidence that current laboratory levels suggesting normal range may not be accurate when it comes to treating low levels of thyroid hormones, and the scale of what is considered normal has been adjusted several times. Doctors are urged not to overlook low normal readings anymore, as these may be medically significantly.
When the body fails to produce adequate T4, this can be discovered via blood sampling, as stated. Initial tests may be called TSH tests and only evaluate the level of thyroid stimulating hormone. If TSH is not correct, doctors might then order T4 and T3 tests to look at the specific levels of each hormone. Should thyroxine be low, doctors may suggest supplementation with medications called levothyroxine. This is the chemical version of T4, which is also known by the brand name Synthroid®.
There is a body of evidence suggesting supplementation with levothyroxine may not be as helpful as supplementation with the brand-name drug. Part of this may relate to the instability of drug versions of T4. Different formulations, may actually work differently and a high number of people report problems with generic types, especially when switching from one generic manufacturer to another. There are still many in the medical field who argue that generic thyroxine is just as good as Synthroid®, but a number of doctors now appear to agree with patients who use thyroid supplementation that there is an appreciable difference.
As important as having adequate thyroxine is, it’s also important not to have too much. High levels may lead to weight loss, sweating, tremor, and enlargement at the neck where the thyroid gland is located. Prolonged hyperthyroidism may cause significant hair loss, heart problems, and development of osteoporosis. When these symptoms are present, the goal is to reduce amount of T4 and T3. This might be accomplished by removing the thyroid gland and supplementing with levothyroxine or by giving medications that may suppress thyroid gland function.