Thyroid.

A Thyroid disease or the Thyroid disorder causes  disturbance in the Thyroid function resulting in abnormal thyroid secretion levels of  the thyroid hormones, T3 and T4. This gives rise to thyroid disease symptoms such as weight loss or weight gain and some such symptoms which are explained in the subsequent posts related to the thyroid disease. You may have an overactive thyroid or a thyroid gland that does not function well. 

Thyroid Gland.

Just as we have a Circulatory System, a Skeletal System, a Nervous System, we also have in our body , The Endocrine System.

The word “Endocrine” comes from two Greek words : endo and  krinein, which mean  “secreting internally”. And  therefore as the meaning suggests, the endocrine system consists of glands which secrete hormones internally into the blood and not through ducts into the blood stream. Various such glands are the Pituitary gland, the Adrenal gland, the Thyroid gland, etc.

The normal thyroid gland has a butterfly shape  and wraps itself on the trachea (windpipe) in  front of the  neck, just above the collar  bone.

It has two lobes on either side of the trachea, joined by a narrow band of thyroid tissue called the isthmus.

Thyroid Function.

• The Thyroid gland takes up the iodine and amino acid called Tyrosine from the food we eat  and forms thyroid hormones called T3 (Thyroxine) and T4 (Triiodothronine).
• T3 is the more active hormone and controls most of the metabolic activity. T4 is ultimately converted into T3 in the blood.
• The thyroid releases these hormones into the blood when commanded by the Pituitary gland situated in the brain.
• T3 and T4 control metabolism in the body cells, which is conversion of calories and oxygen into energy.
• The metabolism in our body is totally dependent on the thyroid  gland.

Normal Thyroid Levels.

Normal TSH range >  0.5 to 5.5.  Since 2003 this normal range has been revised to 0.3 to 3.3 However some labs do still use the old normal range.

Normal T3 range. Total T3 is 80 to 220 points.

Free T3 is 2.3 to 4.2 points.

Normal T4 Level. Total T4 is 4.5 to 12.5

Free T4 is 0.7 to 2.0

How is the Thyroid gland controlled.

• The  functioning of the thyroid gland is controlled by a small peanut sized gland, situated at the base of  the brain, called the Pituitary gland. It secretes the hormone called Thyroid Stimulating hormone.(TSH).
• When the levels of T3 and T4 in the blood fall, and the requirement for metabolism arises, the pituitary gland secretes TSH (thyroid stimulating hormone)  into the blood , thereby stimulating the thyroid to release T3 and T4 into the blood. When high levels of T3 and T4 are not required, the pituitary stops the secretion of the TSH and the thyroid stops releasing T3 and T4 into the blood.
• The pituitary gland is in turn controlled by another gland in the brain called the Hypothalamus, which secretes the Thyrotropin regulating hormone (TRH).

Thyroid Disease or Thyroid Disorders.

1. Hyperthyroidism results due to an overactive thyroid gland. Discussed in detail in the following post on hyperthyroidism.
2. Hypothyroidism is  a below normal functioning thyroid gland. Discussed in detail in the following post on hypothyroidism.
3. Goitre is enlargement of the thyroid gland. At times, it presses on the neighboring  structures such as the trachea or the esophagus and can cause difficulty in breathing and swallowing. Treatment is surgical removal. Details are explained in non toxic goiter.
4. Malignancy of the Thyroid gland begins in a thyroid nodule. Malignancy is found in 7% of the people with thyroid nodule  , but life expectancy is quite long.
5. Inflammation of the Thyroid (Thyroiditis) is an inflammation of the thyroid and causes pain and fever. It may manifest as symptoms of hyper or hypo thyroidism and treated accordingly.
6. Thyroid Nodule : The thyroid may develop a nodular growth. It is usually benign and present in more than 40% of the population.

Our Other Posts on Thyroid.

1)  Thyroid 2)  Hyperthyroidism. 3)  Hypothyroidism. 4) Non Toxic Goiter 5)Graves’ Disease.

Related posts:

1. Thyroid – Non Toxic Goiter.
2. Graves’ Thyroid Disease or Diffuse Toxic Goiter.