This is the most common thyroid disorder. It means the thyroid gland is not active enough, making too little thyroid hormone. The most common cause of hypothyroidism is an autoimmune disorder in which the body makes antibodies against the thyroid gland. Another frequent cause is having had treatment for an overactive thyroid gland by radioactive iodine therapy or surgery.
An unusual condition, secondary hypothyroidism, occurs if the pituitary gland ceases to direct the thyroid gland to make thyroid hormones.
There are several risk factors for hypothyroidism:
- Sex. Women are three times more likely than men to develop it.
- Age. Most people with the condition are older than 60.
- A history of thyroid surgery
- Use of provocative drugs, including lithium and amiodarone
- Having other immune conditions, such as type 1 diabetes, celiac disease or rheumatoid arthritis
- Having Turner syndrome, a genetic condition that affects females
- Pregnancy. Women who are pregnant or who have delivered within 6 months are more likely to have hypothyroidism.
Symptoms of hypothyroidism differ, are often subtle and usually start slowly.
- Coarse, dry, and thickened skin is the commonest symptom
- Tiredness (fatigue)
- Being troubled by cold
- Altered menses; these may be increased, irregular or even absent.
- Infertility in either sex
- Loss of libido, sexual impotence
- Slow speech
- Droopy eyelids
- Puffy and swollen face
- Weight gain
- Sparse, coarse, and dry hair
- Hand tingling or pain (carpal tunnel syndrome)
- Slow pulse
- Muscle cramps
- Thinning or loss of eyebrow hair
These symptoms may look like other health problems and are commonly mistaken for depression.
Evaluating hypothyroidism requires an exam and blood testing for the thyroid hormone levels. The most sensitive test is for Thyroid-Stimulating Hormone, which is elevated when the thyroid is underactive.
Therapy for hypothyroidism is straightforward: thyroid hormone is given to replace what is missing. Modern thyroid therapy starts with T4 (thyroxine), which is identical to the hormone that constitutes 90% of the production of a healthy thyroid. Tri-iodothyronine (T3), which is a more active form of thyroid hormone, can be given if T4 therapy is ineffective. The goal of treatment is to normalize your level of thyroid hormone. Quiet conversation, physical exam and blood tests help us judge the correct dose of thyroid hormone. Younger patients and women who develop hypothyroidism after delivery often resolve their disease spontaneously, but patients past their reproductive years usually require therapy for life.