The general fatigue associated with hypothyroidism is caused by a number of different mechanisms but is primarily the result of an overall decrease in metabolism.

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Hypothyroidism is most commonly caused by autoimmune thyroid disease, a disorder in the body that causes the immune system to mistakenly attack the body’s thyroid gland.

The attack renders the thyroid incapable of producing enough thyroid hormone to keep your metabolism working at a normal pace, leading, ultimately, to fatigue and other symptoms.

Almost 5 percent of the United States population has been diagnosed with hypothyroidism, while 4 to 20 percent of people have what doctors call “subclinical hypothyroidism,” which, most experts agree, is the equivalent of the early stages of mild thyroid failure.

Symptoms of Hypothyroidism

Hypothyroidism causes your brain and body to slow down. Those affected feel tired, “heavy,” and slow, both physically and mentally. It is important to determine whether you carry many of the symptoms of hypothyroidism.

Typical symptoms of hypothyroidism include:

• Fatigue
• Weight gain or obesity
• Depression
• Sensitivity to cold
• Thin and friable (easily crumbled) nails
• Muscle aches
• Headaches
• Decreased libido
• Low basal body temperature (consistently below 98.6°F)
• Weakness
• Cold intolerance
• Water retention
• Dry skin
• Thinning of the lateral 1/3 of the eyebrows
• Menstrual irregularities
• Memory loss and cognitive impairment
• High cholesterol levels
• Decreased tolerance for exercise

What Causes Fatigue in People with Hypothyroidism?

The general fatigue associated with hypothyroidism is caused by a number of different mechanisms but is primarily the result of an overall decrease in metabolism.

Cells throughout the entire body rely on thyroid hormone to perform their basic metabolic functions. A lack of thyroid hormone results in a slower basal metabolic rate. When metabolism is low, activity of the mitochondria within cells is impaired, which leads to low levels of ATP (adenosine triphosphate—an energizer in the cells) and, ultimately, to generalized fatigue. In addition to general fatigue, low ATP levels also contribute to muscle symptoms such as increased muscle tension, pain, and weakness.

Furthermore, patients with hypothyroidism are known to produce more lactic acid, which also contributes to muscle pain, muscle cramps, and fatigue.

Many individuals with hypothyroidism may notice fatigue especially with physical exertion. This is caused in part by the direct effects of thyroid hormone on heart tissue. Without enough thyroid hormone, the heart slows down and decreases the amount of blood pumped, reducing the flow of oxygenated blood to the tissues.

Because thyroid hormone also influences blood sugar metabolism and blood flow to the brain, thyroid hormone deficiency also can cause fatigue by decreasing the amount of glucose and oxygen available to the brain. This leads to the lethargy, forgetfulness, and depression common to those with hypothyroidism.

Diagnosis of Hypothyroidism

TSH, or thyroid stimulating hormone, is a hormone released by the pituitary gland in the brain. Its function is to stimulate thyroid hormone production by the thyroid gland. TSH can be measured in a simple blood test. This test is the most important factor for diagnosing hypothyroidism.

TSH levels within the normal range indicate a healthy thyroid. However, when the TSH level is high, your clinician will request a blood test for T4 levels. Many conventional clinicians will diagnose hypothyroidism when TSH is abnormally high and T4 is abnormally low. This combination indicates that the brain is trying very hard to stimulate the thyroid gland to make T4 thyroid hormone, but the thyroid gland is not able to do it.

Anyone who feels constantly tired, “in a fog,” cold, and unable to lose weight or keep weight off despite dieting should be checked for hypothyroidism.

If your thyroid gland is not producing enough thyroid hormone, you will continue to feel debilitating fatigue, despite whatever positive steps you might take.

For more information about treating hypothyroidism, purchase Fatigue: Causes & Fatigue at www.UniversityHealthNews.com.