The thyroid is a small gland about two inches across that lies under the Adam's apple in the lower neck. The butterfly-shaped gland secretes thyroid hormones which control the body's metabolism and supply oxygen to the cells.
Thyroid hormones affect many body functions including respiratory rate, heart rate, the number of calories burned, fertility and digestion.
A sluggish thyroid, or hypothyroidism, is common and more readily diagnosed now that test result level parameters have been expanded.
Thyroid Hormones
Thyroid hormone levels are used to determine if a person has a slow thyroid. Following are the various thyroid levels and what they mean:
- T4 Thyroxine: largest amount of hormone produced by thyroid, but converts to T3
- T3 Triiodothyronine: most active thyroid hormone.
- TSH: thyroid stimulating hormone, regulated by the pituitary gland
The thyroid makes mostly T4 but a large amount of T4 is converted to T3 in the liver and other tissue. A person's health and their bodies' needs from moment to moment control the conversion. The largest amount of T3 and T4 in the bloodstream is carried bound to a protein that is called thyroxine-binding globulin. Only a little bit of T3 and T4 circulate freely around in the bloodstream but it is the free T3 and T4 that is active.
To make thyroid hormone, the thyroid gland needs iodine, which comes from food and water. However, if the gland gets too much iodine, it will begin to produce less of the thyroid hormone.
Symptoms of Hypothyroid
An under-active or slow thyroid has definitive symptoms, including the following:
- fatigue, lack of energy
- depression and decreased concentration
- constipation and digestion problems
- weight gain
- loss of hair, dry coarse hair
- dry skin
- menstruation problems
- cold hands and feet, sensitivity to cold
Slow Thyroid and Being Tired and Fatigued
One of the most common symptoms of hypothyroidism is fatigue. It is not unusual for people with an under-active thyroid to feel tired even if they have a full night's sleep. A slow thyroid can also cause insomnia.
Causes of Slow Thyroid
The most common cause of slow thyroid is a disorder of the thyroid gland itself, such as Hashimoto's thyroiditis, a chronic autoimmune inflammation of the thyroid. Hypothyroid also develops after treatment for thyroid cancer or overactive thyroid (hyperthyroid). Iodine deficiency can cause hypothyroidism as well as some hereditary conditions.
A slow thyroid is common, especially among the elderly and women. Symptoms of suspected slow thyroid can be easily checked with a simple blood test. Endocrinologists and practitioners who specialize in testing for free T3 and T4 and TSH levels are a good resource for diagnosing a slow thyroid.
References:
The New Harvard Guide to Women's Health, Carlson, Eisenstat and Ziporyn, 2004
Mayoclinic.com, "Hypothyroidism" (accessed June 2, 2010)
Elizabeth Richards - Elizabeth Richards has published almost 200 articles for Suite101 since 2007 as a Contributing and Feature Writer.
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