Symptoms of Hyperthyroidism

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When your thyroid gland is overactive (hyperthyroidism) and produces too much hormone, your body's metabolism speeds up. Considering the whole-body effects this can have, a variety of symptoms may result, including weight loss, irritability, irregular heart rhythm, tremor, insomnia, hair loss, and more. Hyperthyroidism also carries some potential complications with it, such as bone weakening, atrial fibrillation, and pregnancy concerns, though these are more common when the disease goes untreated or uncontrolled.

Frequent Symptoms

Most people with hyperthyroidism experience one or more of the following symptoms. While these symptoms typically come on gradually, they may begin abruptly, especially in young people. On the other hand, older people with hyperthyroidism tend to have fewer and less noticeable symptoms than younger people. 

As you can see, hyperthyroidism can affect the entire body, top to bottom:

Temperature

Increased sweating, as the body produces more heat, is another common symptom of hyperthyroidism. This excess sweating is linked to heat intolerance, which means a person may have a hard time tolerating a warm environment or activities that further increase heat production, like exercise.

Skin/Hair/Nails

In addition to thinning hair and a softening of the nails, the skin of a person with hyperthyroidism is often unusually smooth and warm, due to a rise in blood flow.

Heart

Due to increased pumping of the heart, a person with hyperthyroidism will often notice their heart racing or pounding.

Irregular heart rhythms (called arrhythmias) and high blood pressure may also occur with an overactive thyroid gland.

Lung

Shortness of breath, especially with exercise, is common in older people with hyperthyroidism. It occurs as a result of a weakness of their breathing muscles, as well as an increased demand for oxygen within the body.

Intestines 

Digestive symptoms, like dyspepsia and frequent bowel movements/diarrhea, may occur in hyperthyroidism as a result of the increase in gut motility.

Weight loss, despite an increase in appetite, is due to both the increase in gut mobility (which leads to fat malabsorption) and metabolic rate (which means the body is burning through calories quicker than normal). While this increase in metabolism may initially energize people, eventually they become fatigued as the body tires out.

Neck

An enlargement of the thyroid gland (called a goiter) may occur in some people with hyperthyroidism, causing potential symptoms like a sore throat and/or neck discomfort. Neck swelling may become noticeable, especially when a person tries to put on a tie or scarf.  A goiter may eventually cause problems swallowing or even breathing. 

Urinary Tract

Urinating more often, during the daytime and nighttime, is common in people with hyperthyroidism. 

Reproductive System

Due to an alteration of sex hormones in the body, women with hyperthyroidism may develop infrequent menstrual periods. With severe hyperthyroidism, a woman may stop menstruating (amenorrhea).

Since the excess thyroid hormone converts testosterone to estradiol (a type of estrogen), men may experience a decrease in their sex drive, erectile dysfunction, and swelling of their breast tissue (gynecomastia).

In addition, sperm production is often reduced or abnormal.

Brain and Nerves

A tremor of the hands often occurs in hyperthyroidism, along with behavioral and personality changes, such as depression, anxiety, nervousness, and/or irritability. Insomnia, as well as difficulties with concentrating or remembering things, are also frequently reported in hyperthyroidism.

Other 

Other medical problems, like anemia (a decrease in red blood cells) and abnormal liver function tests, can be the first clue that a person has an overactive thyroid.

Complications

There are a few major complications that may result from having hyperthyroidism, especially if left untreated.

Eye 

Some people develop eye issues (called Graves' ophthalmopathy), which may cause gritty, red eyes or protrusion of the eyes due to swelling behind the eyeballs. In severe cases, double vision can develop.

Bone 

Hyperthyroidism is linked to osteoporosis, which causes bone weakening, making a person more prone to breaking bones with even minor bumps or falls.

Heart

In hyperthyroidism, there is a high risk of developing atrial fibrillation, especially in older people. Atrial fibrillation is a common heart arrhythmia that can lead to serious problems like stroke or heart failure.

Thyroid Storm

Thyroid storm is a rare but very serious, potentially life-threatening condition that occurs in people with untreated hyperthyroidism. It may also be triggered by a stressful event like surgery, trauma, or infection.

Thyroid storm is characterized by exaggerated symptoms of hyperthyroidism, such as a very fast heart rate, high fever, diarrhea, agitation, delirium, and/or decreased consciousness.

Pregnancy

While mild hyperthyroidism in pregnancy does not usually cause problems for a mother and her baby, moderate-to-severe hyperthyroidism in a mother can lead to various complications. 

For the baby, according to the American Thyroid Association, uncontrolled or untreated hyperthyroidism of the mother during pregnancy is associated with size that is small for gestational age, preterm birth, stillbirth, and possibly congenital malformations. 

For the mother, potential complications of untreated hyperthyroidism include pre-eclampsia and, rarely, thyroid storm. 

Fetal Neonatal Hyperthyroidism

For a pregnant woman with Graves' disease (the most common cause of hyperthyroidism in pregnancy), there is a small risk that her baby will develop hyperthyroidism before birth (called fetal thyrotoxicosis) or be born with hyperthyroidism (called neonatal hyperthyroidism). 

Some babies are born hyperthyroid while others take days or weeks (up to three) to develop hyperthyroidism. The hyperthyroidism develops as the antithyroid drug the mother was taking. which was passing through the placenta to the baby, wears off after birth.

While uncommon, hyperthyroidism may also occur in the newborns of mothers who have a history of treated Graves' disease (meaning their disease is in remission). This is why it's important to notify your doctor of any history of thyroid disease, in addition to active thyroid disease. 

If your baby develops hyperthyroidism, some symptoms may include: 

  • Low birth weight
  • An unusually small head circumference (microcephaly)
  • Warm, moist skin
  • Irritability and poor sleep
  • Fast heartbeat
  • A dangerous accumulation of fluid, known as fetal hydrops (rare)

When to See a Doctor

If you are concerned you (or a loved one) is experiencing one or more symptoms of an overactive thyroid gland, be sure to see your doctor for a proper evaluation. The good news is that your thyroid function can be easily checked with a simple blood test, called the thyroid-stimulating hormone (TSH) test. 

Of course, seek medical attention right away if you notice alarming symptoms, like an irregular pulse, problems breathing, or delirium. 

Lastly, if you are taking antithyroid medications for hyperthyroidism and considering pregnancy, it's important to seek guidance from your general practitioner and, perhaps, an endocrinologist. You want to be sure your thyroid function is well controlled prior to and during pregnancy. 

Sources:

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Garber J et al. Clinical Practice Guidelines for Hypothyroidism in Adults: Cosponsored by the American Association of Clinical Endocrinologists and the American Thyroid Association. Endocr Pract. 2012 Vol 18 No. 6 Nov-Dec;18(6):988-1028.  

Kurtoglu S, Ozdemir A. Fetal neonatal hyperthyroidism: diagnostic and therapeutic approachment. Turk Pediatri Ars. 2017 Mar;52(1):1-9. doi:​ 10.5152/TurkPediatriArs.2017.2513

Lin TY et al. Incidence of abnormal liver biochemical tests in hyperthyroidism. Clin Endocrinol (Ocf). 2017 May;86(5):755-59. 

Luewan S, Chakkabut P, Tongsong T. Outcomes of pregnancy complicated with hyperthyroidism: a cohort study. Arch Gynecol Obstet. 2011 Feb;283(2):243-7.