The thyroid is a butterfly-shaped gland that sits at the base of the throat above the collarbone. Its primary function is to produce growth hormones critical to brain and spine development. These hormones enter the bloodstream and are distributed to tissue throughout the body.
Thyroid hormones are crucial for the proper functioning of:
Heart and other organs
When the thyroid gland fails to produce the necessary quantities of these hormones, the condition is known as underactive thyroid or hypothyroidism. The main cause of hypothyroidism in the US is Hashimoto's thyroiditis.
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Hashimoto's thyroiditis is an autoimmune disorder affecting thyroid function. The term 'thyroiditis' means inflammation of the thyroid gland. With Hashimoto's disease, the thyroid is chronically inflamed due to the autoimmune properties of the disease.
A healthy immune system works by producing antibodies that attack and destroy viruses, bacteria, cancer cells, and other unwanted substances recognized as 'foreign' to the body. If you have an autoimmune disorder, your antibodies begin to destroy your own healthy tissue instead of intruders. This autoimmunity can lead you to develop weakness and dysfunction in those organs or parts of the body that have been under attack.
In Hashimoto's thyroiditis, when the antibodies attack the thyroid tissue, they leave behind inflammatory cells that build up over time. This causes damage to the gland, making it incapable of producing the level of thyroid hormones needed by the body. When the thyroid gland does not function normally, every organ is negatively affected.
Hashimoto's thyroiditis occurs most frequently in middle-aged female patients, with higher numbers seen after the age of 60. While men are also susceptible, female patients are two to eight times more likely to have thyroid disease. It is more common in women who were of smaller stature when they were young and had a lower birth weight,¹ two elements frequently found in teenagers with Hashimoto's thyroiditis.
Hashimoto's disease usually occurs later in life. However, as with many autoimmune disorders, the condition can develop at any time. The prevalence of Hashimoto's disease is 1.2%² in the pediatric population. When the disease affects children, it is most likely to develop during the teenage years.
Hashimoto's thyroiditis can be present long before the symptoms of hypothyroidism are noticeable. It is more often found in adolescents with other autoimmune diseases like:
Or genetic conditions such as:
During childhood, thyroid hormones play a key role in the development and maturation of most organs, especially the brain and spine. When Hashimoto's thyroiditis develops in children, it will usually manifest as goiter and the presence of autoantibodies in the blood.
Symptoms of Hashimoto's thyroiditis in teenagers closely echo those seen in adults, but they may be more difficult to recognize. Teenagers will often experience the following:
Slowed growth in height or short stature
Enlarged thyroid gland (goiter)
Appearance younger than age
Slower development of breasts
Late menstrual start
Heavy menstrual bleeding or irregular periods
Increased testicular size in boys
Delayed puberty in both genders
Poor muscle tone
Slow heart rate
Hoarseness of the voice
Swollen hands and feet
Muscle aches and weakness
While the above symptoms of hypothyroidism are easier to recognize, teenagers with Hashimoto's may also exhibit other, more subtle and generalized symptoms, including:
Tendency to oversleep
Difficulties concentrating and poor school performance
While some of these signs and symptoms might be blamed on other conditions and influences, when considered collectively, their cause is more likely to be due to Hashimoto's thyroiditis.
As with adults, it's possible for teenage patients not to develop any symptoms at all and still have a high thyroid antibody count, signifying Hashimoto's thyroiditis.
Some adolescents are more likely to develop Hashimoto's thyroiditis. Risk factors include:
Gender: Girls³ are more likely to develop Hashimoto's disease in adolescence than boys
Other autoimmune disorders: Patients with autoimmune disorders such as type 1 diabetes or lupus are more likely to develop other autoimmune conditions such as Hashimoto's thyroiditis
Some environmental factors can contribute to increased risk in certain areas of the population over others. These seem to work in combination with genetic factors to increase the overall risk of thyroid autoimmunity.
When thyroid disease is suspected in teenagers, their medical practitioner will first obtain a history of the symptoms and then perform a physical examination and some diagnostic testing.
During the history-taking part of the evaluation, the medical professional will ask questions about any symptoms the teen may be experiencing and how long they have been going on.
When performing the physical exam, they will check for an enlarged thyroid gland and any associated physical abnormalities, such as signs of delayed puberty.
Diagnostic testing will be in the form of lab work. The blood is tested to measure the levels of thyroid-stimulating hormone (TSH), thyroid hormones T3 and T4, and thyroid peroxidase (TPO) antibodies.
When the thyroid gland does not produce enough T3 and T4, the pituitary gland gets the message. It secretes TSH to make the thyroid work harder, so elevated TSH levels indicate low thyroid function.
TPO antibodies are known to be present in patients with Hashimoto's disease. Elevated levels mean there are lots of autoantibodies attacking the thyroid tissue.
If your teenager is found to have thyroid autoantibodies and is diagnosed with Hashimoto's thyroiditis, their treatment will depend on several factors. These include the following considerations:
Is the patient's thyroid function normal (normal TSH, T4, and T3 levels)? Most children with early Hashimoto's thyroiditis present with normal thyroid hormone levels and no symptoms. If this is the case, the doctor will probably monitor your teen's TSH and TPO antibody numbers over time to see if they increase and thyroid hormone levels to see if they decrease, all indicating thyroid dysfunction. Only a small percentage⁴ of children progress to hypothyroidism.
Is the patient asymptomatic? If your teenager has low thyroid hormone levels and elevated TSH and TPO antibodies but no symptoms of hypothyroidism, the treatment may start with regular monitoring of their labs. These children are more likely to develop hypothyroidism over time, so they need to be followed closely.
Is the patient at risk and symptomatic with low thyroid hormone levels? These children are more likely to develop long-term thyroid dysfunction, so they are usually started on treatment right away. Replacement hormones will need to be taken daily, with regular monitoring of blood levels several times a year.
Is the patient having symptoms of hyperthyroidism (rapid heart rate, tremor, anxiety)? This is quite rare in children. It can occur during the initial phase of Hashimoto's thyroiditis when antibodies attack the thyroid gland, and stored hormones are released. The prognosis in these cases is quite favorable as there is a high likelihood of a return to normal thyroid function over several months. Once the initial labs indicate Hashimoto's disease, some children may be placed on medication, but all will be followed closely for resolution.
The most effective hormone therapy for those who need medication is synthetic T4 hormone, called levothyroxine, to replace what the body is not producing. It comes as a pill or liquid taken by mouth daily on an empty stomach. Dosages will be adjusted in accordance with blood test results throughout the year.
Once the correct dose of thyroid replacement medication is determined, most of the symptoms will resolve. It is important for your teen not to miss doses or stop the medicine abruptly without discussing it with their doctor.
When left untreated, hypothyroidism caused by Hashimoto's thyroiditis can lead to complications, some of which are serious. The untreated patient may develop:
A goiter that could cause a hoarse voice and eventually interfere with the ability to swallow or breathe
Heart problems, including an enlarged heart and eventual heart failure
Mental health issues, including depression and slowed mental functioning
A thyroid gland that begins to shrink and may become fibrotic (thickened and/or scarred)
If you observe the signs and symptoms of hypothyroidism or Hashimoto's thyroiditis in your teenager, consult your medical professional as soon as possible. Hypothyroidism is not routinely screened for in children (just the newborn screening done right after birth).
If you or a close family member has been diagnosed with hypothyroidism or Hashimoto's thyroiditis, it is even more important to make your child's doctor aware of this because the disorder is commonly seen in families.
If your teenager is showing slowed growth and development and a tendency toward being overweight, you should ask your doctor about testing their thyroid function. You will want to discuss other signs such as behavioral situations and a possible inability to focus in school. If your teenager's tests result in a diagnosis of Hashimoto's thyroiditis, they will likely be referred to an endocrinologist.
The thyroid is a key component of our metabolism. Thyroid hormones play a large role in the growth and development of all parts of our bodies. When the thyroid cannot produce thyroid hormones such as TSH and T4, hypothyroidism is the result.
Hashimoto's thyroiditis might be uncommon in teenagers, but it does occur and is sometimes difficult to detect. If your teenager is showing signs or symptoms of hypothyroidism or Hashimoto's disease, you will want them to see their physician for an evaluation.
Hashimoto's disease | National Institute of Health
Hypothyroidism | Medscape
Hashimoto disease | Endocrine Society