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5 Surprising Facts about “Low Thyroid” in Children and Teens

What parents should know about hypothyroidism

Reviewed by pediatric endocrinologist Andrew J. Bauer, MD, medical director of The Thyroid Center at Children’s Hospital of Philadelphia

More kids and teens than ever seem to have hypothyroidism—a damaged or sluggish thyroid gland that doesn’t produce enough thyroid hormone—says pediatric endocrinologist Andrew J. Bauer, MD, medical director of The Thyroid Center at Children’s Hospital of Philadelphia. A low thyroid can interfere with normal growth and development and even put puberty on hold. The fatigue it causes can interfere with performance at school and leave kids without enough energy for sports and play, too.

hypothyroidism in kids

“We used to think that one or two in 100 kids and teens would develop hypothyroidism, but now it looks like two to three in 100,” says Dr. Bauer, co-author of a recent review of childhood thyroid disorders for pediatricians and family doctors published in JAMA Pediatrics. “We don’t know the full extent of hypothyroidism in young people in the United States, but rates seem to be increasing along with rates of other autoimmune conditions. We don’t know why. It may be that more children and teen are being tested, so we’re finding it more often. The “hygiene hypothesis” —that living in clean environments early in life may throw off the immune system—is another possible explanation.”

As families hear more about this thyroid condition, here’s what parents should know:

#1: Hypothyroidism is the most common thyroid disorder in babies, kids and teens.

Routine testing at birth uncovers hypothyroidism in one in every 1,500-3,000 newborns. The cause is usually a problem with development of the thyroid gland— the bow-tie-shaped gland at the base of the neck. “Early diagnosis and treatment of thyroid hormone deficiency is crucial to ensure normal physical development and normal brain development,” Dr. Bauer says. “Screening is part of all newborn screening programs in the United States.”

However, hypothyroidism can also develop later in childhood or the teen years. Risk is four times higher in girls than in boys. And young people with a family history of autoimmune diseases or who have Down syndrome, Turner syndrome, type 1 diabetes or celiac disease are also at higher risk.

The most common cause of this “acquired” hypothyroidism: An immune system attack on cells in the thyroid gland.  Other factors that can harm the thyroid gland or its ability to produce thyroid hormones include radiation for cancers of the head and neck, some drugs (including lithium, some epilepsy drugs and chemotherapy drugs called tyrosine kinase inhibitors) and, rarely, iodine deficiency.  Thanks to “iodized” salt (fortified with iodine) and the natural iodine in dairy products, fish and eggs, this nutrition problem is relatively rare in the U.S.  

#2: Symptoms can hide in plain sight.

Tiredness, constipation, feeling cold and dry skin and hair are classic red flags – but parents and doctors may not suspect a sluggish thyroid at first as these symptoms are common complaints of everyday life, not specific to thyroid disease.  A slow-down in growth, a delay in developing at puberty and, for girls, irregular menstrual periods are also key symptoms. “Delays in diagnosing thyroid problems are also common in kids and teens with hyperthyroidism (a thyroid gland that produces too much thyroid hormone) because of the cross-over in behavior that is similar to anxiety and/or attention deficit disorders,” Dr. Bauer says. “We’re also seeing the flip side —more parents legitimately concerned about their child’s tiredness or weight want to know if it’s a thyroid problem. If parents are worried—especially if their child is not growing well, is not going through puberty when they should be, or if they develop unexplained and consistent signs or symptoms consistent with hypo- or hyperthyroidism – it’s worth mentioning to the doctor.” 

#3: For most kids and teens, overweight isn’t caused by a sluggish thyroid.

“Overweight and obesity are rarely caused by hypothyroidism in children and teens,” Dr. Bauer says. “Parents wonder if a thyroid problem is the cause, especially when they’re doing all they can to help a child eat a healthy diet and be active. Children with hypothyroidism may sometimes look as if they’re carrying a few extra pounds because they’re not getting taller. But most of the time, it’s being overweight that can lead to changes in thyroid hormone levels not the other way around.”

Extra body fat can increase levels of the hormone leptin, which in turn can increase levels of thyroid stimulating hormone even when the thyroid is working normally. That can look like subclinical hypothyroidism. “With weight loss, thyroid stimulating hormone levels return to normal,” Dr. Bauer says

#4: Parents can do a quick check at home.

An enlarged thyroid gland is an important clue to hypothyroidism and hyperthyroidism. “Along with other symptoms, it can help your doctor decide whether it is worthwhile performing thyroid testing,” Dr. Bauer explains. “However, you can have hypothyroidism without an enlarged thyroid.” Parents can do the basic check at home, he says. “We don’t encourage parents to try to be doctors, but having your child look up at the ceiling while you look at their neck is a pretty easy. If you can see the outline of the thyroid in this position, then the thyroid is enlarged.”

The thyroid gland is located at the base of the neck. It extends about an inch to either side of the center line of the neck. Check for an enlarged thyroid by looking at this area of the neck in three positions:

1. while your child looks straight ahead, with their chin parallel to the floor.

2. while your child looks up with her head tilted back a little and her chin pointing upward so that her neck is extended.

3. while she swallows as she looks up.

If you can see the shape of the thyroid gland through the skin or can see a slight bulge on one or both sides, it may mean her thyroid is enlarged. That’s worth making an appointment with the doctor. “Parents can also watch our Youtube video demonstrating how to do this exam, at https://www.youtube.com/watch?v=Z9norsLPKfU,” Dr. Bauer says.

#5: Taking synthetic thyroid hormone is the gold standard treatment…sometimes with an unexpected effects for students.

Doctors diagnose hypothyroidism by checking for symptoms, taking a family history, examining a child’s thyroid gland and testing levels of thyroid-stimulating hormone (TSH) and free T4 (free thyroxine). High TSH and low T4 can mean hypothyroidism. Levels of anti-thyroid antibodies, which may be elevated, may also get checked. “If a child or teen has hypothyroidism, the standard treatment is levothyroxine—synthetic thyroid hormone to replace hormones the thyroid isn’t producing in large-enough quantities,” Dr. Bauer says.

The dose is customized for each child, so that thyroid hormone levels stay within a healthy range. Your child’s doctor will recheck his or her thyroid every three to six months until he or she reaches full height—with more frequent checks after a change in dose. “This should take care of delays in growth and puberty, prevent learning delays, improve energy levels and get a young person’s life back to normal,” Dr. Bauer says.

But sometimes, the “brain fog” or fatigue of hypothyroidism doesn’t completely lift with levothyroxine, he notes. “If that’s the case with your child, it’s worth asking the doctor whether adding a second thyroid hormone, called T3, would be beneficial,” Dr. Bauer says. “We are beginning to see benefits for some adults and children using combined T3 and T4 treatment, although, this approach remains controversial and additional research into this approach is needed.” This is likely the main reason why some patients feel better on ‘natural’ thyroid hormone – it is not that it is a ‘natural’ product compared to a ‘synthetic’ product but that the ‘natural’ version of thyroid hormone has both T3 and T4 in the formulation.

Meanwhile, some parents notice a surprising “side effect” of treatment: Kids who were quiet and relatively inactive now have plenty of energy – and may be more interested in playing and just running around than sitting down to do homework. “There are usually kids with severe hypothyroidism who get all their homework done and don’t get distracted because they were too tired to do much else but sit around,” Dr. Bauer says. “After treatment, all of a sudden you’ve got a typical eight-year-old who’s full of energy. It can be an adjustment for the patient and the parents.”  


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Hypothyroidism in Children