The thyroid gland is one of the vital organs of the body and is situated at the front and lower part of the neck. It consists of two lateral lobes (each lobe is about 5.0 cm in length, 2.5 cm in width and 2.5 cm in thickness) which are fixed on their back surfaces to the sides of the trachea, and are joined by a band (called isthmus), which crosses the front of the trachea, to which it is also firmly attached. An adult weight of the thyroid gland is 20-25 grams.

The thyroid gland secretes essential hormones called thyroxine or tetraiodothyronine (called T4), and also a small amount of triiodothyronine (called T3). These hormones are responsible for various functions / activities of the body. They regulate/maintain the metabolism of the body. Overactivity or underactivity of the thyroid gland occurs whenever the thyroid secretion increases or decreases as a result of various disorders of the thyroid gland.

More about T4 and T3

Normal life is hardly possible if the levels of these hormones in the blood are disturbed. As stated above, they are produced by the thyroid gland, and for their production, the thyroid gland needs a proper and regular supply of iodine. This supply of iodine to the thyroid gland is met from the food and water we take in our daily life. The iodine in the thyroid gland is converted into T4' which is the chief hormone of the thyroid gland.

Some vital information about iodine and thyroid hormones

Iodine is very essential for the body, and more precisely for the thyroid gland, so that the gland can provide a constant supply of its hormones for the maintenance of the body.

The thyroid gland has got a great affinity for iodine, and goes on taking its supply from the blood. However, if the person takes more dietary iodine than is required by the gland, the excess is excreted by the kidneys.

The thyroid gland functions well on its own, supplying the required hormones, as per demand of the body. Even for emergency purposes, it keeps a reserve of these hormones in the gland itself.

When the demand of the body for such hormones increases during a pregnancy or in lactation, or when the child is growing, i.e. during puberty, the thyroid gland may have to work more to meet the needs of the body, so that it may get enlarged temporarily. It is common to examine both boys and girls in their growing years, with enlarged thyroid glands. One only needs to assure them, emphasizing that such an enlargement of the thyroid gland is only physiological- called puberty goiter.

Cancer of the Thyroid Gland

Early detection of cancer of the thyroid gland should be given priority while dealing with any problem related to this gland.

There may be a solitary nodule/ s in a thyroid gland, or even a nodule/ s of a multinodular goiter, which may be malignant. Or, the whole gland may undergo a malignant change.

Hence, nodule/s in a thyroid gland must be given prompt consideration, and if the whole gland is enlarged, one needs to palpate, to check if there is any hard/indurated area of the thyroid gland, which may be of a malignant nature. It may happen, especially when the swelling of the thyroid gland is of recent origin, and has rapidly increased in size.

Tests for detection of thyroid cancer:

Ultrasonographic examination of the thyroid gland and/or computed tomographic (CT) scanning/magnetic resonance imagining (MRI), as well as fine needle aspiration cytology (FNAC), help in establishing the diagnosis of the malignancy of the thyroid gland. A radioisotope scanning of the thyroid gland may also be required in some of the cases. It tells precisely about the hyperactive areal s in the thyroid gland.