Thyroid underactive living in teenagers

Overview

An underactive thyroid (hypothyroidism) happens when the thyroid gland in your neck doesn't make enough thyroid hormone. This hormone controls your body's metabolism, or how your body uses energy. Without enough, many body processes slow down.

Hypothyroidism is less common in teenagers than in adults, but it still affects many adolescents. It is more frequent in girls and in teens with a family history of thyroid problems.

Teenagers of any age can develop an underactive thyroid, but it is most often seen in girls. It can also affect teens with certain conditions such as Turner syndrome, Down syndrome, or type 1 diabetes.

Symptoms

Common symptoms

• Feeling tired or sluggish
• Weight gain without a clear reason
• Feeling cold when others are warm
• Dry or pale skin
• Constipation
• Hair that is thin or falls out easily
• Depression or low mood
• Trouble concentrating or memory problems

Symptoms in children

• Slow growth or shorter height than peers
• Delayed puberty (e.g., no menstrual periods in girls)
• Poor performance in school
• Feeling very sleepy during the day
• Puffy face or eyelids

Symptoms in older adults

• Memory loss or confusion
• Hoarse voice
• Thinning eyebrows
• Joint or muscle aches
• Hearing loss

Causes

Main causes

• Autoimmune disease (Hashimoto's thyroiditis) – the body's immune system attacks the thyroid gland
• Treatment for an overactive thyroid (radioactive iodine or surgery)
• Radiation therapy to the neck or head for cancer
• Certain medicines (e.g., lithium, amiodarone)
• Iodine deficiency (rare in countries with iodised salt)
• Congenital hypothyroidism (present from birth)

Risk factors

• Having a family member with thyroid disease
• Being female
• Having another autoimmune condition (like type 1 diabetes or celiac disease)
• Having Turner syndrome or Down syndrome
• Previous radiation to the neck area

When to see a doctor

See a doctor urgently if:

• If you have symptoms that are severe or worsening quickly, such as extreme tiredness, confusion, or shortness of breath
• If you have a swelling in the neck that makes it hard to breathe or swallow

Book a routine appointment if:

• If you notice any of the common symptoms listed above and they last for more than a few weeks
• If your growth or puberty seems delayed compared to your peers
• For a routine check-up if you have a family history of thyroid problems

Diagnosis

Your doctor will ask about your symptoms and do a physical exam, feeling your neck for any swelling. They will then order a blood test to check your thyroid function.

Tests that may be done

• TSH (thyroid-stimulating hormone) test – a high TSH level suggests your thyroid is underactive
• Free T4 test – measures the actual thyroid hormone in your blood
• Thyroid antibody test – to check for autoimmune causes

What to expect at your appointment

The blood test is simple and you will get results in a few days. If you are diagnosed, your doctor will explain your treatment plan and how to manage it day by day. Follow-up blood tests will be done to make sure your dose is right.

Treatment

Treatment involves replacing the missing thyroid hormone with a daily medicine taken as a tablet. This medicine is usually taken once a day, on an empty stomach, about 30 minutes before breakfast. It is important to take it at the same time every day. Your doctor will start with a low dose and adjust it based on your blood tests. Treatment is lifelong, but with it you can feel completely back to normal.

Self-care at home

• Take your thyroid medicine exactly as prescribed every day – never skip a dose
• Keep a routine, like taking it when you first wake up
• Tell your doctor about any other medicines or supplements you take, as they can affect how your thyroid medicine works
• Eat a balanced diet and get enough sleep
• Listen to your body – rest when you need to
• Keep all your follow-up appointments and blood tests

Medical treatments

The main treatment is a daily synthetic thyroid hormone (levothyroxine) that replaces the hormone your body is missing. Your doctor will decide the right starting dose based on your age, weight, and blood test results. The dose may need adjusting as you grow. Regular blood tests are done to keep your hormone levels in the normal range.

When is surgery considered?

Surgery is not usually needed for an underactive thyroid. It is only considered in very rare cases, such as if the thyroid gland becomes very large and causes breathing or swallowing problems, or if cancer is suspected.

Living with this condition

Living with an underactive thyroid means taking your medication daily and having regular check-ups. Once your hormone levels are stable, you can do all the things your friends do – school, sports, hobbies, and hanging out. You may need to adjust your dose during growth spurts or if you gain or lose a lot of weight.

Lifestyle tips

• Build a daily routine around your medicine
• Get regular physical activity to help with energy and mood
• Manage stress with deep breathing, hobbies, or talking to someone you trust
• Sleep at least 8–10 hours a night as a teen
• Avoid smoking and vaping – they can affect your thyroid

Diet and exercise

There is no special diet for hypothyroidism, but eating a balanced diet is always a good idea. Include plenty of fruits, vegetables, whole grains, and lean protein. If you take your thyroid medicine, avoid eating high-fiber foods or taking calcium or iron supplements within 4 hours of your dose. Exercise is encouraged and can help boost your energy and mood.

Mental health and emotional wellbeing

Hypothyroidism can affect your mood, making you feel sad, irritable, or anxious. It can also make it hard to concentrate at school. These feelings often improve once your hormone levels are normal with treatment. If you continue to feel depressed or worried, talk to your doctor or a trusted adult – there is help.

Prevention

Most cases of underactive thyroid cannot be prevented, especially if they are due to an autoimmune condition. However, congenital hypothyroidism is often detected early through newborn screening, which allows treatment to start right away.

Screening programmes

Newborn screening for congenital hypothyroidism is routine in many countries. There is no routine screening for teenagers unless they have symptoms or risk factors. If you have a family history of thyroid problems, talk to your doctor about whether testing is right for you.

Complications

If left untreated

• Slowed growth and delayed puberty
• Poor school performance and trouble concentrating
• Heart problems, including a slow heart rate and higher risk of heart disease
• High cholesterol
• Severe depression or other mood disorders
• In very rare cases, a life-threatening condition called myxedema coma (extreme hypothyroidism)

Long-term outlook

With proper treatment, the outlook for teenagers with an underactive thyroid is excellent. You can grow and develop normally, do well in school, and enjoy a full, active life. The key is taking your medication consistently and seeing your doctor for regular check-ups. Most teens with hypothyroidism live just as long and as healthily as anyone else.

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