Hypothyroidism is a condition characterized by abnormally low thyroid hormone production. There are many disorders resulting in hypothyroidism which may directly or indirectly involve the thyroid gland.

Thyroid hormone affects growth, development and many cellular processes and hence inadequate thyroid hormone has many ill effects on body.

Hypothyroidism is a very common condition and is more common in women than in men, and its incidence increases with age.

Common causes of hypothyroidism in adults are listed below:

• Hashimoto's thyroiditis (Autoimmune disease in which thyroid gland is enlarged which decrease ability to make thyroid hormones)
• Lymphocytic thyroiditis (inflammation caused by a particular type of white blood cell known as a lymphocyte)
• Thyroid destruction (from radioactive iodine or surgery)
• Pituitary or hypothalamic disease
• Medications
• Severe iodine deficiency

Patients with mild hypothyroidism may have no signs or symptoms. 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 are listed below:

• Fatigue
• Weakness
• Weight gain or increased; difficulty losing weight
• Coarse, dry hair
• Dry, rough pale skin
• Hair loss
• Cold intolerance (person can't tolerate cold temperatures like those around)
• Muscle cramps and frequent muscle aches
• Constipation
• Depression
• Irritability
• Memory loss
• Abnormal menstrual cycles
• Decreased libido

Each individual patient may have any number of these symptoms, and they will vary with the severity of the thyroid hormone deficiency and the length of time the body has been deprived of the proper amount of hormone.

The diagnosis of hyperthyroidism is based on basis of complete physical examination by the physician who then decides to go for the specific diagnostic tests which helps him to confirm the diagnosis.

The presence of above mentioned symptoms and signs strongly suggests the need for diagnostic testing for hyperthyroidism which is listed below:

• Blood levels of T3, T4 and TSH: To confirm the presence of excessive thyroid hormone (but this test do not point to a specific cause).
• A combination of the patient's clinical history, antibody screening and a thyroid scan to rule out underlying thyroid problem.

To identify pituitary or hypothalamic, an MRI of the brain and other studies may be required which differ from case to case.

Since hypothyroidism develops from a shortage of thyroid hormone, the most effective treatment is generally thyroid hormone supplementation which is either natural hormones extracted from the thyroid glands of animals or synthetic hormones (such as levothyroxine).

Although, treatment provides the necessary hormone control, hypothyroidism often continues throughout life, and the patient may require lifelong follow-up and medication to control the condition.