Hypothyroidism
Hypothyroidism, also known as underactive thyroid, occurs when the thyroid gland does not make enough thyroid hormone to keep the body working properly. The thyroid gland is a small, butterfly shaped gland located in the front of the neck. It secretes hormones (T3, T4) that control metabolism. If there is not enough thyroid hormone in the bloodstream, the body’s metabolism may slow down. If left untreated, it may lead to other severe problems like goiter, myxedema, obesity, heart disease and infertility.
Hypothyroidism occurs more often in women and usually at middle age. It tends to run in families. Some babies are born without a thyroid gland or with a gland that does not work. If left untreated, it can lead to physical and mental retardation.
Types
There are two types of hypothyroidism:
Primary hypothyroidism
Primary hypothyroidism occurs when the thyroid gland does not make sufficient thyroid hormone. The most common cause is Hashimoto’s thyroiditis. Other common causes include radioactive iodine treatment, surgical removal of thyroid and certain medications. Primary hypothyroidism is more common than secondary hypothyroidism.
Secondary hypothyroidism
It is a condition in which thyroid gland itself is normal, but the pituitary gland doesn’t stimulate the thyroid to produce more hormone. This failure of the pituitary gland to secrete a hormone to stimulate the thyroid gland is called secondary hypothyroidism. Secondary hypothyroidism is less common than primary hypothyroidism.
Diagnosis
Hypothyroidism is difficult to diagnose because symptoms of hypothyroidism are sometimes confused with other conditions. The most efficient way is by measuring TSH level in blood. In addition to the blood test, examination of the patient can help diagnose hypothyroidism.
Blood test
Hypothyroidism can be diagnosed by checking Thyroid stimulating hormone (TSH) and Thyroxine T4 levels in the blood. If the test shows elevated TSH level and low level of T4 in the blood it may be a sign of hypothyroidism.
Physical examination
Your doctor will examine you for any sign such as an enlarged thyroid gland, and weight gain.
What causes hypothyroidism?
Hypothyroidism can be caused by:
- Hashimoto disease: Hashimoto disease, an autoimmune disease occurs when the body’s immune system mistakenly attacks and destroys your thyroid cells. It is the most common cause of hypothyroidism in adults.
- Iodine deficiency: Iodine is an essential component of thyroid hormones. Lack of iodine in the diet can prevent the thyroid gland from making hormones.
- Family history: Having a family history of thyroid disease is also a risk factor of hypothyroidism.
- Medicines: Certain medicines like lithium and amiodarone can interfere with thyroid hormone production.
- Treatment for hyperthyroidism: Sometimes, treatment for hyperthyroidism like radio iodine therapy or surgery ends up causing hypothyroidism.
- X-rays: Radiation to the neck or thyroid can lead to hypothyroidism.
- Pituitary gland dysfunction: In some cases, hypothyroidism is caused by a decrease in production of TSH by the pituitary gland.
Symptoms
The symptoms of hypothyroidism develop slowly that you may not notice them until the condition is advanced. It can be mistaken for other conditions like depression. Common symptoms include-
- Weight gain
- Sensitivity to cold temperatures
- Tiredness
- Depression
- Hair loss
- Constipation
- Menstrual irregularities
- Dry skin
- Muscle cramps
- Brittle nails
Treatment
The goal of the treatment is to bring the level of thyroid hormone back to normal. It can be done with thyroid hormone replacement therapy.
Medication
Levothyroxine is the drug of choice. It is a synthetic version of thyroxine (T4) and works exactly like body’s natural hormone. This is more stable and longer lasting form of thyroid hormone and needs to be taken once a day on an empty stomach. The therapy begins with low doses which may be increased gradually. The dose is adjusted every six weeks until the correct dose of levothyroxine is achieved. A routine blood test is necessary to ensure that the patient is taking the correct dose. Most of the patients require lifelong thyroid hormone therapy.
Iodine Supplements
If hypothyroidism is caused by iodine deficiency, then iodine supplements are recommended.
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