Hypothyroidism is a condition in which there is low thyroid hormone production. Because thyroid hormone affects growth, development, and many cellular processes, low thyroid hormone has many consequences on the body. Thyroid hormones are produced by the thyroid gland. This gland is located in the lower part of the neck in the front side. The gland wraps around the windpipe and has a shape of a butterfly, formed by two lobes and attached by a middle part isthmus. The thyroid gland utilizes iodine present in our regular food and iodized salt that is used in food to produce thyroid hormones. The two most important thyroid hormones are thyroxine (T4) â€" 99% and triiodothyronine (T3) â€" 1%. Biologically most activity is T3. Once released from the thyroid gland into the blood, a large amount of T4 is converted into T3. The thyroid is regulated by another gland located in the brain, called the pituitary. The pituitary is regulated in part by the thyroid through "feedback" mechanism of thyroid hormone on the pituitary gland and by another gland in the brain called the hypothalamus. The hypothalamus releases a hormone called thyrotropin releasing hormone (TRH), which sends a signal to the pituitary to release thyroid stimulating hormone (TSH). In turn, TSH sends a signal to the thyroid to release thyroid hormones. If a disruption occurs at any of these levels, a disturbance in thyroid hormone production may result in a deficiency of thyroid hormone which results in hypothyroidism. The rate of thyroid hormone production is controlled by the pituitary gland. If there is an insufficient amount of thyroid hormone circulating in the body to support normal functioning, the release of TSH is increased by the pituitary gland to stimulate more thyroid hormone production. In contrast, when there is an excessive amount of circulating thyroid hormone, TSH levels goes down as the pituitary attempts to decrease the production of thyroid hormone.

In persons with hypothyroidism, there is a persistent low level of circulating thyroid hormones. The symptoms of hypothyroidism are often gross, which means they can mimic the symptoms of many other conditions. The symptoms generally become more obvious as the condition worsens and the majority of these complaints are related to a metabolic slowing of the body.

Common symptoms of hypothyroidism:

• Tiredness


• Irritability and Depression


• Weight gain despite of controlled food intake


• Heightened sensitivity to Cold


• Sleepiness and laziness


• Dry, hair and skin


• Constipation


• Muscle aches, tenderness and stiffness Pain


• Heavy menstrual periods


• Brittle fingernails and hair


• Increased cholesterol levels


• Decreased concentration


• Edema of the legs

As the disease becomes more severe, there may be puffiness around the eyes, a slowing of the heart rate, a drop in body temperature, and heart failure. In its most advanced stage , severe hypothyroidism may lead to a life-threatening coma, which is known as myxedema - coma. In a severely hypothyroid individual, a myxedema coma tends to be triggered by severe illness, surgery, stress, or traumatic injury. This condition requires hospitalization and immediate treatment with thyroid hormones given through parenteral route. Properly diagnosed, hypothyroidism can be easily and completely treated with thyroid hormone replacement. On the other hand, untreated hypothyroidism can lead to an enlarged heart, worsening heart failure, and an accumulation of fluid around the lungs. A diagnosis of hypothyroidism can be suspected in patients with fatigue, cold intolerance, constipation, and dry, flaky skin. A blood test is needed to confirm the diagnosis. When hypothyroidism is present, the blood levels of thyroid hormones can be measured directly and are usually decreased. However, in early hypothyroidism, the level of thyroid hormones may be normal. Therefore, the main tool for the detection of hyperthyroidism is the measurement of the TSH. As mentioned earlier, TSH is secreted by the pituitary gland. If a decrease of thyroid hormone occurs, the pituitary gland reacts by producing more TSH and the blood TSH level increases in an attempt to encourage thyroid hormone production. This increase in TSH can actually precede the fall in thyroid hormones by months or years Thus, the measurement of TSH should be elevated in cases of hypothyroidism. However, there is one exception. If the decrease in thyroid hormone is actually due to a defect of the pituitary or hypothalamus, then the levels of TSH are abnormally low. This kind of thyroid disease is known as "secondary" or "tertiary" hypothyroidism. A special test, known as the TRH test, can help distinguish if the disease is caused by a defect in the pituitary or the hypothalamus. This test requires an injection of the TRH hormone and is performed by an endocrinologist (hormone specialist). The blood work confirms the diagnosis of hypothyroidism, but does not point to an underlying cause. A combination of the patient's clinical history, antibody screening, and a thyroid scan can help diagnose the precise underlying thyroid problem more clearly. If a pituitary or hypothalamic cause is suspected, an MRI of the brain and other studies may be warranted.

Hypothyroidism may be due to a number of different factors such as:

• Autoimmune disease (Hashimoto thyroiditis).


• Treatment for hyperthyroidism.


• Radiation therapy.


• Thyroid surgery.


• Medications like lithium, used for psychiatric illness.

Less often, hypothyroidism may result from one of the following:

• Congenital disease.


• Pituitary disorder


• Pregnancy


• Iodine deficiency.

Untreated hypothyroidism can lead to a number of health problems:

• Goiter


• Heart problems


• Mental health issues.


• Myxedema


• Infertility


• Birth defects.