Hypothyroidism is a condition in which the thyroid gland, located in the front of the neck, does not produce enough thyroid hormones, which control overall metabolism and many bodily functions. Hypothyroidism can have several causes, including an autoimmune disorder (Hashimoto’s disease), in which the body’s immune system mistakenly destructs its own thyroid gland. In teens, this is perhaps the most common cause of underactive thyroid, compared to other causes of the condition. Other causes could be certain medications or pituitary hypothyroidism, in which the pituitary gland, which controls the thyroid gland. Sometimes, a cause cannot be identified.

While the condition typically develops in adult life — its incidence increases with age — congenital hypothyroidism can occur in children and even newborns. One out of every 4,000 to 5,000 thousand babies born in the United States has hypothyroidism.

Undiagnosed hypothyroid children may experience slowed growth rate.

Additional symptoms include sluggishness, pallor, dry and itchy scalp, increased sensitivity to cold and constipation. If untreated, the condition may have devastating effects, such as stunted physical growth and mental retardation.

Symptoms

• Slowed growth rate
• Puffy face
• Swollen hands and feet
• Poor muscle tone
• Sluggishness, sleepiness
• Constipation
• Fatigue
• Dry, itchy scalp
• Dry, coarse skin
• Heavy menstruation in girls
• Mood swings
• Weight gain
• Hoarse cry or voice
• Dry, coarse skin
• Enlarged thyroid gland (goiter)

Diagnosis

A physician will suspect underactive thyroid if several of the above symptoms are present; however, a definitive diagnosis can be easily made by testing the level of a pituitary hormone called thyroid-stimulating hormone (TSH). If the thyroid is producing normal levels of thyroid hormones, TSH will be within normal range. However if the thyroid is underactive, then the pituitary starts secreting more TSH to jump-start the sluggish thyroid. Thus, a higher-than-normal level of TSH indicates an underactive thyroid. Most newborns are tested for hypothyroidism within 72 hours of birth as part of a routine screen for other conditions.  

When to Call for Help

If you see any of the above symptoms in your baby, infant or child — particularly slow growth — call your pediatrician.  

Treatment

Replacement therapy with synthetic thyroid hormones in the form of a single daily tablet is usually given. Thyroid hormones are critical for normal brain development in babies and children, therefore treatment with the correct dose of synthetic hormone is very important. Because the body can require higher doses of synthetic hormone over time, the child should be retested periodically to make sure the right amount of hormone is given and the dose is adjusted as needed.