TSH stands for thyroid stimulating hormone. The pituitary gland produces TSH to stimulate the thyroid gland, which is located in the neck, to produce the hormones triiodothyronine (T3) or thyroxine (T4) that control how the body uses and stores energy.
When the thyroid gland is not functioning properly and not producing enough thyroid hormones, this can result in high levels of TSH in the blood, which is an indicator of hypothyroidism (underactive thyroid). Hypothyroidism is an endocrine disorder that occurs when a person’s body does not make enough thyroid hormone.
One form of hypothyroidism is autoimmune thyroid disease, also called Hashimoto’s disease or Hashimoto's thyroiditis. Myxedema coma is a severe form of hypothyroidism.
The opposite of hypothyroidism is hyperthyroidism, a condition in which the body produces too much thyroid hormone.
What Are Symptoms of Hypothyroidism?
Symptoms of hypothyroidism may be subtle or vague and some people may have no symptoms. When symptoms of hypothyroidism occur, they may include:
- Fatigue
- Loss of energy
- Lethargy
- Sleepiness
- Decreased appetite
- Weight gain
- Cold intolerance
- Dry skin
- Hair loss
- Weakness in the extremities
- Muscle pain
- Joint pain
- Mood swings
- Depression
- Cognitive impairment
- Difficulty concentrating
- Forgetfulness/memory problems
- Constipation
- Menstrual disturbances
- Fertility problems
- Decreased sweating
- Numbness, tingling, and nerve entrapment syndromes
- Hearing loss
- Blurred vision
- Feeling of fullness in the throat
- Hoarseness
- Nail problems such as infection, vertical white ridges on the nails, nail splitting, brittle nails, slow nail growth, and nails lifting up
Symptoms more specific to Hashimoto thyroiditis include:
- Painless thyroid enlargement
- Feeling of fullness in the throat
- Exhaustion
- Temporary neck pain, sore throat, or both
Symptoms of myxedema coma (severe hypothyroidism) include:
- Altered mental status
- Low core body temperature (hypothermia)
- Slow heart rate
- Too much carbon dioxide (CO2) in the bloodstream
- Low blood sodium levels
- Enlarged heart, fluid around the heart, cardiogenic shock, and ascites
- Nonpitting edema
What Causes Hypothyroidism?
In the U.S. and other countries where iodine intake is adequate, the most common cause of hypothyroidism is autoimmune thyroid disease (Hashimoto’s disease).
Worldwide, iodine deficiency is the main cause of hypothyroidism.
How Is Hypothyroidism Diagnosed?
A medical history and physical examination is performed, but blood tests are used to diagnose hypothyroidism.
Blood tests used to diagnose hypothyroidism include:
- Thyroid-stimulating hormone (TSH)
- Thyroxine (T4)
- Triiodothyronine (T3)
- Thyroid antibody tests
What Is the Treatment for Hypothyroidism?
Hypothyroidism is treated with thyroid hormone replacement therapy.
- Levothyroxine (LT4) (Synthroid, Levoxyl, Levothroid, Unithyroid) is the most common treatment
- Sometimes, another form of thyroid hormone, liothyronine (T3) (Cytomel, Triostat), may be given with T4
- Since T4 is converted into triiodothyronine (T3) in other organs, most studies do not show an advantage of combining T3 and T4 over using T4 alone
- Women may need higher doses of T4 during pregnancy
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https://www.uptodate.com/contents/hypothyroidism-underactive-thyroid-beyond-the-basics?search=Hypothyroidism&topicRef=15438&source=see_link
https://www.aad.org/public/diseases/a-z/thyroid-disease-skin-changes