What is hypothyroidism?
Hypothyroidism is a condition characterized by abnormally low thyroid hormone production. There are many disorders that result in hypothyroidism. These disorders may directly or indirectly involve the thyroid gland. Because thyroid hormone affects growth, development, and many cellular processes, inadequate thyroid hormone has widespread consequences for the body.

This article will focus specifically on hypothyroidism in adults

What are thyroid hormones?
Thyroid hormones are produced by the thyroid gland. This gland is located in the lower part of the neck, below the Adam's apple. The gland wraps around the windpipe (trachea) and has a shape that is similar to a butterfly - formed by two wings (lobes) and attached by a middle part (isthmus).

The thyroid gland uses iodine (mostly available from the diet in foods such as seafood, bread, and salt) to produce thyroid hormones. The two most important thyroid hormones are thyroxine (T4) and triiodothyronine (T3), which account for 99% and 1% of thyroid hormones present in the blood respectively. However, the hormone with the most biological activity is T3. Once released from the thyroid gland into the blood, a large amount of T4 is converted into T3 - the active hormone that affects the metabolism of cells

Treatment:

A variety of factors affect the decision of whether to treat a patient for hypothyroidism, which dosage to begin with, and how rapidly treatment should be started or increased:

• First, an elevated TSH (thyrotropin) level should be confirmed and thyroxine (T4) level determined. Other thyroid tests may also be helpful.

• Measuring cholesterol levels is also important.

Doctors should also consider:
 

• Age of the patient

• Presence of other medical problems that may benefit from thyroid replacement treatment (such as heart failure or depression)

• Presence of other medical problems that thyroid replacement therapy may worsen (such as osteoporosis)