Hypothyroidism: Description, Causes and Risk Factors: Alternative Name: Underactive thyroid, athyrea. The thyroid is a 2-inch-long, butter?y-shaped gland weighing less than an ounce. It is located in the front of the neck below the larynx or voice box, and comprises two lobes, one on either side of the windpipe. The thyroid is one of a group of glands that are part of the endocrine system. The thyroid gland makes two thyroid hormones, triiodothyronine or T3 (C15H12I3NO4) and thyroxine or T4 (C15H11I4NO4). Thyroid hormones affect metabolism, brain development, breathing, heart and nervous system functions, body temperature, muscle strength, skin dryness, menstrual cycles, weight, and cholesterol levels. Women are much more likely than men to develop hypothyroidism. The disease is also more common among people older than age 60. Hypothyroidism is common in whites and Asians. African-Americans are at lower risk. Studies have shown that nearly 25 million suffer from the disease, with half remaining undiagnosed. Hypothyroidism has several causes, including:

• Hashimoto's disease.
• thyroiditis, or in?ammation of the thyroid gland.
• Congenital hypothyroidism, or hypothyroidism that is present at birth.
• Surgical removal of part or all of the thyroid gland.
• Radiation treatment of the thyroid.
• Some medications such as heart medications, cancer medications, bipolar disorder medications, and kidney cancer medications.
• Less commonly, hypothyroidism is caused by too much or too little iodine in the diet or by abnormalities of the pituitary gland.

Note:

• Soy does not cause hypothyroidism, but it does interfere with the body's ability to absorb thyroid replacement therapy.
• The amounts of broccoli, cabbage, and brussels sprouts that people eat in a normal diet do not cause hypothyroidism.
• There is no evidence that some people's thyroid gland makes enough hormone but it does not get to the body's cells.

Symptoms: When thyroid hormone levels are too low, the body's cells cannot get enough thyroid hormone and the body's processes start slowing down. As the body slows, you may notice that you feel colder, you tire more easily, your skin is getting drier, you are becoming forgetful and depressed, and you have started getting constipated. Symptoms vary from person to person. Some common symptoms of hypothyroidism are:

• Fatigue.
• Drowsiness.
• Forgetfulness.
• Weight gain.
• Puffy face.
• Cold intolerance.
• Joint and muscle pain.
• Constipation.
• Dry, brittle, and thin hair.
• Decreased sweating.
• Heavy or irregular menstrual periods and impaired fertility.
• Depression and anxiety.
• Slowed heart rate.

Diagnosis: Physical exam: The doctor will check your thyroid gland and look for changes such as dry skin, swelling, slower reflexes, and a slower heart rate. Medical and family history: You should tell your doctor:

• About changes in your health that suggest that your body is slowing down.
• If you have ever had thyroid surgery.
• If you have ever had radiation to your neck to treat cancer.
• If you are taking any of the medicines.
• Whether any of your family members have thyroid disease.

Tests May Include: Blood tests: There are two blood tests that are used in the diagnosis of hypothyroidism.

• TSH (thyroid-stimulating hormone) test: This is the most important and sensitive test for hypothyroidism. It measures how much of the thyroid hormone T4 (thyroxine) the thyroid gland is being asked to make. An abnormally high TSH means hypothyroidism: the thyroid gland is being asked to make more T4 because there is not enough T4 in the blood. In most labs, the normal range for TSH is 0.4 mU/L to 4.0 mU/L. If your TSH is above 4.0 mU/L on both a first test and a repeat test, you probably may have hypothyroidism.
• T4 tests: Most of the T4 in the blood is attached to a protein called thyroxine-binding globulin. The “bound” T4 cannot get into body cells. Only about 1%-2% of T4 in the blood is unattached (“free”) and can get into cells. The free T4 and the free T4 index are both simple blood tests that measure how much unattached T4 is in the blood and available to get into cells.

Note:

• Low body temperature is not a reliable measure of hypothyroidism.
• Saliva tests for thyroid disease are not accurate to confirm hypothyroidism.

Women with hypothyroidism should discuss their condition with their doctor before becoming pregnant. Uncontrolled hypothyroidism raises the chance of miscarriage, preterm delivery, and preeclampsia, which is a potentially serious complication that increases blood pressure. Treatment: Hypothyroidism is treated with synthetic thyroxine, which is identical to the T4 made by the thyroid. The exact dose will depend on the patient's age and weight, the severity of the hypothyroidism, the presence of other health problems, and whether the person is taking other drugs that might interfere with how well the body uses thyroid hormone. The only dangers of thyroxine are caused by taking too little or too much. If you take too little, your hypothyroidism will continue. If you take too much, you will develop the symptoms of hyperthyroidism — an overactive thyroid gland. Disclaimer: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.