Thyroxine is a hormone (body chemical) made by the thyroid gland in the neck. It is carried round the body in the bloodstream. It helps to keep the body's functions (the metabolism) working at the correct pace. Thyroid hormone helps the body use energy, stay warm, keeps your brain thinking clearly, your heart pumping rhythmically, and basically maintains harmony among all organs in your body.

Women are five to eight times more likely to have thyroid dysfunction than men, but most don't know they have it. Women often overlook their symptoms or mistake them for symptoms of other conditions. Women are at particularly high risk for developing thyroid disorders following childbirth. Symptoms such as fatigue and depression are common during this period, but these are also symptoms of thyroid disease. Types of Thyroid Disorders The thyroid gland can malfunction in one of three ways: It can release too little thyroxine resulting in a condition known as hypothyroidism (underactive thyroid). It can release too much thyroxine, resulting in a condition known as hyperthyroidism (overactive thyroid). Its tissue can overgrow, resulting in a nodule, a small lump in part of the gland. Most nodules are harmless growths, but some are cancerous. However, despite this relatively low incidence, thyroid cancer is currently the fastest growing cancer in women.

Hypothyroidism Hypothyroidism means that the thyroid gland does not make enough thyroxin. It is often called an underactive thyroid. When thyroid hormone levels are too low, the body’s cells can’t get enough thyroid hormone and the body’s processes start slowing down. For example, the body makes less heat and less energy, and organs like the brain and bowels move more slowly. 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.

You may also have body changes that you can’t feel. For example, you may not know that cholesterol is building up in your blood and .plaque. is hardening your arteries, increasing your risk for heart attack. So hypothyroidism doesn’t just cause symptoms. It can make other conditions worse. Hypothyroidism is more common in women than men. Its symptoms include Fatigue Weight gain Cold intolerance Dry or brittle hair Memory problems Irritability and depression Higher cholesterol levels leading to increase in the risk of heart disease Slower heart rate Constipation, or sluggish bowel Excessive menstrual bleeding Infertility Miscarriage

Hypothyroidism can occur spontaneously, develop during or after pregnancy or after treatment for hyperthyroidism. You can be born with it or it can be caused by Hashimoto's thyroiditis. Hashimoto's thyroiditis is an autoimmune disease. That means the immune system attacks the body's healthy tissues instead of fighting off invading bacteria or viruses. In this case, the immune system produces antibodies to attack the thyroid gland as if it were a foreign substance that needed to be destroyed. The resulting damage leads to reduced production of Thyroid hormone. Hyperthyroidism In contrast, if you have hyperthyroidism, you make too much thyroxine. This causes many of the body's functions to speed up.

Your symptoms could include: Weight loss despite a good appetite Heat intolerance Frequent bowel movements Tremors Nervousness and irritability Thyroid gland enlargement Sleep disturbances Fatigue weakness in your muscles—especially in the upper arms and thighs menstrual flow may lighten and menstrual periods may occur less often

The most common cause (in more than 70% of people) is overproduction of thyroid hormone by the entire thyroid gland. This condition is also known as Graves’ disease. Graves’ disease is caused by antibodies in the blood that turn on the thyroid and cause it to grow and secrete too much thyroid hormone. This type of hyperthyroidism tends to run in families and it occurs more often in young women. How are thyroid disorders diagnosed? Thyroid disorders can be hard to diagnose because their symptoms can be linked to many other health problems. Blood Tests : The diagnosis of thyroid disorders will be confirmed by laboratory tests that measure the amount of thyroid hormones— thyroxine (T4) and triiodothyronine (T3)—and thyroid-stimulating hormone (TSH) in your blood. A high level of thyroid hormone in the blood plus a low level of TSH is common with an overactive thyroid gland. The reverse is true of hypothyroidism. Thyroid Scan : If blood tests show that your thyroid is overactive, a thyroid scan will find out if your entire thyroid gland is overactive or whether you have a toxic nodular goiter or thyroiditis (thyroid inflammation). A test that measures the ability of the gland to collect iodine (a thyroid uptake) may be done at the same time as the scan. Treatment of an underactive thyroid Hypothyroidism can’t be cured. No one has discovered a way to make the thyroid gland start to work normally again. But with daily treatment, taken every day for life, hypothyroidism can be completely controlled in almost every patient. It’s treated by replacing the amount of hormone that your own thyroid can no longer make, to bring your T4 and TSH back to normal levels. So even if your thyroid gland can’t work right, T4 replacement can restore your body’s thyroid hormone levels and your body’s function. Synthetic thyroxine pills (also called L-thyroxine or levothyroxine) contain hormone exactly like the T4 that the thyroid gland itself makes. Treatment of an overactive thyroid Unlike hypothyroidism, no single treatment is best for all patients with hyperthyroidism. The appropriate choice of treatment will be influenced by your age, the type of hyperthyroidism that you have, the severity of your hyperthyroidism, other medical conditions that may be affecting your health. Drugs known as antithyroid agents—methimazole or in rare instances propylthiouracil (PTU)—may be prescribed if your doctor chooses to treat the hyperthyroidism by blocking the thyroid gland’s ability to make new thyroid hormone.

Another way to treat hyperthyroidism is to damage or destroy the thyroid cells that make thyroid hormone by using radioactive iodine. The radioactive iodine used in this treatment is administered by mouth, usually in a small capsule that is taken just once. Once swallowed, the radioactive iodine gets into your blood stream and quickly is taken up by the overactive thyroid cells and it destroys them. Your hyperthyroidism can be permanently cured by surgical removal of most of your thyroid gland. Hyperthyroidism & Pregnancy Effects on the mother: Inadequately treated maternal hyperthyroidism can result in early labor and a serious complication known as pre-eclampsia (Development of hypertension in pregnancy). Additionally, women with active Graves’ disease during pregnancy are at higher risk of developing very severe hyperthyroidism known as thyroid storm. Graves’ disease often improves during the third trimester of pregnancy and may worsen during the post partum period. Effects on the Fetus: Uncontrolled maternal hyperthyroidism has been associated with fetal tachycardia (fast heart rate), small for gestational age babies, prematurity, stillbirths and possibly congenital malformations.Graves’ disease is an autoimmune disorder caused by the production of antibodies that stimulate thyroid gland referred to as thyroid stimulating immunoglobulins (TSI). These antibodies do cross the placenta and can interact with the baby’s thyroid to cause fetal or neonatal hyperthyroidism. Hypothyroidism & Pregnancy Effects on the mother: Untreated, or inadequately treated, hypothyroidism has been associated with maternal anemia (low red blood cell count), myopathy (muscle pain, weakness), congestive heart failure, pre-eclampsia, placental abnormalities, low birth weight infants, and postpartum hemorrhage (bleeding). These complications are more likely to occur in women with severe hypothyroidism. Most women with mild hypothyroidism may have no symptoms or attribute symptom they may have as due to the pregnancy. Effects on the Fetus: Thyroid hormone is critical for brain development in the baby. Untreated severe hypothyroidism in the mother can lead to impaired brain development in the baby. This is mainly seen when the maternal hypothyroidism is due to iodine deficiency, which also affects the baby. Therefore checking a woman’s TSH value either before becoming pregnant (pre-pregnancy counseling) or as soon as pregnancy is confirmed is recommended. This is especially true in women at high risk for thyroid disease, such as those with prior treatment for hyperthyroidism, a positive family history of thyroid disease and those with a goiter