What Is Thyroxine?
Thyroxine is the major hormone that the thyroid gland secretes into the bloodstream. Thyroxine and other thyroid hormones play a crucial role in regulating the body’s metabolic rate which controls growth and development.
What Are The Normal Body Thyroxine Levels?
The level of TSH (thyroid-stimulating hormone) in your body determines your thyroxine levels. The TSH notifies the thyroid gland how much thyroxine should be produced. When the TSH level is very high, the thyroxine level becomes low, a condition known as “hypothyroidism.” A normal range for TSH according to clinical research is 0.4 milliunits per liter (mU/L) to 4.0 mU/L. Any TSH level above 4.0 mU/L is an indication of Hypothyroidism.
Causes of Low Thyroxine Levels
There are two common causes of low thyroxine levels. The first is a result of inflammation of the thyroid gland which destroys a large quantity of the cells of the thyroid making them unable to produce enough hormones. The side effects of medical treatment of thyroid conditions is the second cause of low thyroxine levels.
Interesting Questions about Thyroid:
The thyroid is a small, butterfly-shaped gland just below the Adam’s apple. This gland plays a very important role in controlling the body’s metabolism, that is, how the body functions. It does this by producing thyroid hormones (T4 and T3), chemicals that travel through the blood to every part of the body. Thyroid hormones tell the body how fast to work and use energy.
The thyroid gland works like an air conditioner. If there are enough thyroid hormones in the blood, the gland stops making the hormones (just as an air conditioner cycles off when there is enough cool air in a house). When the body needs more thyroid hormones, the gland starts producing again.
The pituitary gland works like a thermostat, telling the thyroid when to start and stop. The pituitary sends thyroid stimulating hormone (TSH) to the thyroid to tell the gland what to do.
About 20 million Americans have some form of thyroid disease. Many are undiagnosed or misdiagnosed. No age, economic group, race, or sex is immune to thyroid disease.
The thyroid gland might produce too much hormone (hyperthyroidism), making the body use energy faster than it should, or too little hormone (hypothyroidism), making the body use energy slower than it should. The gland may also become inflamed (thyroiditis) or enlarged (goiter), or develop one or more lumps (nodules).
| Fact: | Two of the most common thyroid diseases, Hashimoto’s thyroiditis and Graves’ disease, are autoimmune diseases and may run in families. |
| Fact: | Hypothyroidism is 10 times more common in women than in men. |
| Fact: | One out of five women over the age of 75 has Hashimoto’s thyroiditis, the most common cause of hypothyroidism. |
| Fact: | Thyroid dysfunction complicates 5%-9% of all pregnancies. |
| Fact: | About 15,000 new cases of thyroid cancer are reported each year. |
| Fact: | One out of every 4,000 infants is born without a working thyroid gland. |
Hyperthyroidism makes the body speed up. It occurs when there is too much thyroid hormone in the blood (“hyper” means “too much”). Nearly 10 times more frequent in women, it affects about 2% of all women in the United States.
The most common cause of hyperthyroidism, Graves’ disease, is caused by problems with the immune system and tends to run in families. It affects at least 2.5 million Americans, including Olympic athlete Gail Devers who won a gold medal in track after being diagnosed with and treated for Graves’ disease.
Symptoms include:
- fast heart rate
- nervousness
- increased perspiration
- muscle weakness
- trembling hands
- weight loss
- hair loss
- skin changes
- increased frequency of bowel movements
- decreased menstrual flow and less frequent menstrual flow
- goiter
- eyes that seem to be popping out of their sockets.
The symptoms of hyperthyroidism rarely occur all at once. However, if you have more than one of these symptoms, and they continue for some time, you should see your doctor.
Hyperthyroidism from any cause can make the upper eyelids pull back, but Graves’ disease often causes one or both eyes to bulge out of their sockets. This condition, known as exophthalmos, can cause loss of eye muscle control, double vision, and (rarely) loss of vision. Most cases require no treatment, but some patients may need to see an eye doctor (ophthalmologist) for specialized treatment. This may include steroids, radiation, or surgery.
Have more questions? Need more answers? Check our Full Thyroid FAQ
What Happens When Thyroxine Levels Are Low?
When the body’s thyroxine levels become low, it may lead to goiter, which is a swelling of the neck because of an enlarged thyroid gland. The goiter is a result of the high levels of TSH.
Symptoms of Low Thyroxine Levels
Low thyroid thyroxine levels can cause fatigue, weakness, weight gain or increased difficulty losing weight, dry hair, hair loss, muscle cramps and frequent muscle aches, constipation, depression, decreased libido e.t.c. You may likely experience some of these symptoms which may be different from what other patients with the same condition experience. The symptoms vary with how severe the thyroid deficiency is and the length of time the body has to lack the hormone.
Treatment of Low Thyroid Thyroxine Levels
Low thyroxine levels can be corrected by the use of Levothyroxine, a synthetic thyroid hormone. This oral medication and other similar drugs help to bring the hormone to its normal level. Ensure that you consult your doctor before taking any drug.
Thyroxine is an important hormone that regulates metabolic rate. High or low thyroxine levels can lead to abnormal body functioning. It’s important that you visit an endocrinologist if you experience any of the symptoms of hypothyroidism listed in this article.
