Underactive Thyroid: What is Hypothyroidism & Types
Deficiency of the thyroid hormone (THYROXINE) is called Hypothyroidism or Hypothyroid. It can affect any age group though it is most prevalent in older women. It is almost 10 to 20 times more common in females as compared to males. It is one of those conditions which are often present for many years before they can be recognized and treated effectively. Estimated one in every 50 females and one in 1000 men tend to suffer with this condition.
Hypothyroidism can be of two types:
Here the problem lies in the thyroid gland and hence it fails to produce sufficient hormones due to certain causes.
In this type, the pituitary gland is at fault and it is unable to produce sufficient quantity of TSH. Lack of TSH in turn causes decreased production of T3 and T4 by the thyroid gland due to lack of stimulus from the pituitary.
TSH (Thyroid Stimulating Hormone)
Under active thyroid results from an inability of the Thyroid gland to produce adequate Thyroxine hormone. This could be largely due to genetic tendency. It is important to understand that since there is an inability or sluggishness of the thyroid gland, the treatment should ideally be aiming at stimulating the thyroid gland to do its job, rather than simply supplying deficient Thyroxine hormone from outside.
Causes of Underactive Thyroid (Hypothyroidism)
Primary Hypothyroidism or Underactive Thyroid can be caused due to several reasons such as follows:
in food is one of the common causes especially in certain geographic areas of the world.
of the thyroid gland which causes damage or death of the cells of thyroid leading to insufficient production of the hormones is a major cause of Primary hypothyroidism. The main cause of failure of thyroid gland in this manner is by Auto-immune Thyroiditis also known as Hashimoto's Thyroiditis. In this disorder, the patients own immune system causes an inflammation of the gland.
Surgical removal of the thyroid gland or a nodule for treating hyperthyroidism often makes the patient land up with Hypothyroidism after a few years.
Radiotherapy given for hyperthyroidism in order to destroy the hyperactivity of the gland. If larger number of cells are destroyed by the radioactive iodine, the patient may have insufficient hormone production by the remaining cells and this may cause hypothyroidism.
Secondary hypothyroidism is commonly caused by the following:
Failure of the pituitary gland to secrete Thyroid Stimulating Hormone (TSH). This may be caused due to:
• Tumor in the pituitary region
• Infiltration of the pituitary by inflammatory cells from the immune system
• Infiltration of the pituitary by foreign substances (such as iron in Hemochromatosis)
Risk factors for secondary hypothyroidism include being over 50 years old, being female, and having a history of pituitary or hypothalamic dysfunction.
Symptoms of Underactive Thyroid (Hypothyroidism)
The symptoms of hypothyroidism are frequently missed out and especially in elderly females these are mistaken to be symptoms of menopause. The beginning of the symptoms is often not noted markedly and hence the condition remains under-diagnosed.
Patient may experience few of the following symptoms:
- Fatigue, exhaustion
- Weakness, sluggishness
- Unexplained weight gain or increased difficulty losing weight
- Coarse, dry hair and/or thinning of hair
- Hair loss
- Dry, rough, pale and itchy skin
- Cold intolerance (can't tolerate the cold like those around you)
- Depression, mood swings
- Memory loss
- Abnormal menstrual cycles, increased menstrual flow
- Decreased libido
- Infertility, miscarriages
- Difficulty in concentrating
- Thinning and/or falling out of sides of eyebrows
- Puffy, swollen face and dull facial expressions
- Hoarse voice and slow speech
- Goiter (swelling of the thyroid gland)
- Non-pitting edema (swelling)
- Pitting edema (swelling) of the feet