Hypothyroidism: symptoms, causes, diagnosis and remedies

By Cristiano Antonino On May 3, 2023

Hypothyroidism, also called hypoactive thyroid, is when the thyroid gland does not produce enough thyroid hormones to meet your body’s needs

The thyroid gland is a small, butterfly-shaped gland at the front of the neck

Thyroid hormones control the way your body uses energy, so they affect almost every organ in your body, even the way your heart beats.

Without enough thyroid hormones, many of your body’s functions slow down.

Who is more likely to develop hypothyroidism?

Women are much more likely than men to develop hypothyroidism.

The disease is also more common among people over the age of 60.1

Hypothyroidism is more likely to occur if the patient

has had a thyroid problem before, such as a goiter
has had surgery or radioactive iodine to correct a thyroid problem
has received radiation treatment to the thyroid gland, neck or chest
has a family history of thyroid disease
was pregnant within the last 6 months
has Turner syndrome, a genetic disorder that affects women

Your thyroid is also more likely to be underactive if you have other health problems, including

Celiac disease
Sjögren’s syndrome, a disease that causes dry eyes and mouth
pernicious anaemia, a condition caused by a vitamin B12 deficiency
type 1 or type 2 diabetes
rheumatoid arthritis, an autoimmune disease affecting the joints
lupus, a chronic autoimmune inflammatory condition

Is hypothyroidism during pregnancy a problem?

If left untreated, hypothyroidism during pregnancy can affect both mother and baby.

However, thyroid medication can help prevent problems and is safe to take during pregnancy.

Many women taking thyroid hormone medication need a higher dose during pregnancy, so contact your doctor immediately if you find out you are pregnant.

What are the complications of hypothyroidism?

Hypothyroidism can contribute to high cholesterol.

If you have high cholesterol, you should be tested for hypothyroidism.

Rarely, severe untreated hypothyroidism can lead to myxoedema coma, an extreme form of hypothyroidism in which body functions slow down to a life-threatening point.

Myxedema coma requires immediate medical attention.

What are the symptoms of hypothyroidism?

Hypothyroidism has many symptoms that can vary from person to person.

Some common symptoms of hypothyroidism include

fatigue
weight gain
difficulty tolerating cold
joint and muscle pain
dry skin or dry, thinning hair
heavy or irregular menstrual periods or fertility problems
slow heartbeat
depression

Because hypothyroidism develops slowly, you may not notice the symptoms of the disease for months or even years.

Many of these symptoms, particularly fatigue and weight gain, are common and do not necessarily mean that you have a thyroid problem.

What causes hypothyroidism?

Hypothyroidism has several causes, including

Hashimoto’s disease
thyroiditis or inflammation of the thyroid gland
congenital hypothyroidism or hypothyroidism present at birth
surgical removal of part or all of the thyroid gland
radiotherapy of the thyroid gland
certain medications

Less often, hypothyroidism is caused by too much or too little iodine in the diet or by disorders of the pituitary gland or hypothalamus.

Hashimoto’s disease

Hashimoto’s disease, an autoimmune disease, is the most common cause of hypothyroidism.

With this disease, your immune system attacks the thyroid gland.

The thyroid becomes inflamed and cannot produce enough thyroid hormones.

Thyroiditis

Thyroiditis, an inflammation of the thyroid gland, causes leakage of stored thyroid hormone from the thyroid gland.

Initially, the leakage increases hormone levels in the blood, leading to thyrotoxicosis, a condition in which thyroid hormone levels are too high.

Thyrotoxicosis can last for many months.

Subsequently, your thyroid may become underactive and, over time, the condition may become permanent, requiring thyroid hormone replacement.

Three types of thyroiditis can cause thyrotoxicosis followed by hypothyroidism.2

Subacute thyroiditis involves a painfully inflamed and enlarged thyroid gland.

Postpartum thyroiditis develops after a woman has given birth.

Silent thyroiditis is painless, although the thyroid gland may be enlarged. Experts think it is probably an autoimmune condition.

Congenital hypothyroidism

Some children are born with an underdeveloped or malfunctioning thyroid gland.

If left untreated, congenital hypothyroidism can lead to intellectual disability NIH external connection and growth failure, when a child does not grow as expected.

Early treatment can prevent these problems.

That is why most newborns in the US are tested for hypothyroidism.

Surgical removal of part or all of the thyroid gland

When surgeons remove part of the thyroid gland, the remaining part can produce normal amounts of thyroid hormone.

But some people who have this surgery may develop hypothyroidism.

Removal of the entire thyroid always causes hypothyroidism.

Surgeons can remove part or all of the thyroid gland as a treatment for

hyperthyroidism
a large goiter
thyroid nodules, which are non-cancerous tumours or nodules in the thyroid gland that can produce too much thyroid hormone
small thyroid cancer

Thyroid radiotherapy

Radioactive iodine, a common treatment for hyperthyroidism, gradually destroys thyroid cells.

If you receive treatment with radioactive iodine, you will probably eventually develop hypothyroidism.

Doctors also treat people who have tumours of the head or neck with external radiotherapy, which can also damage the thyroid if it is included in the treatment.

Medicines

Some medications can interfere with thyroid hormone production and lead to hypothyroidism, including some

heart medications
bipolar disorder drugs NIH external connection drugs
cancer drugs

Several recently developed cancer drugs, in particular, can directly affect the thyroid gland or affect it indirectly by damaging the pituitary gland.

How do doctors diagnose hypothyroidism?

Your doctor will take your medical history and perform a physical test.

A diagnosis of hypothyroidism cannot be based on symptoms alone because many of its symptoms are the same as those of other diseases.1

That is why your doctor may use various thyroid blood tests and imaging tests to confirm the diagnosis and find the cause.

Since hypothyroidism can cause fertility problems, women who have difficulty getting pregnant are often tested for thyroid problems.

How do doctors treat hypothyroidism?

Hypothyroidism is treated by replacing hormones that your own thyroid gland can no longer produce.

You take levothyroxine, a thyroid hormone medicine that is identical to a hormone produced by a healthy thyroid.3

Usually prescribed in pill form, this medicine is also available as a liquid and as a soft gel capsule.

These new formulas can help people with digestive problems absorb thyroid hormone.

Your doctor may recommend that you take the medicine in the morning before eating.

Your doctor will give you a blood test about 6-8 weeks after you start taking the medicine, adjusting your dose if necessary.

Each time your dose is adjusted, you will have another blood test.

Once you reach a dose that works for you, your doctor will probably repeat the blood test after 6 months and then once a year.

Most likely your hypothyroidism can be completely controlled with thyroid hormone medicine, provided you take the recommended dose according to the instructions.

Never stop taking the medicine without first talking to your doctor.

Taking too much thyroid hormone medicine can cause serious problems, such as atrial fibrillation or osteoporosis NIH external link.1

How does nutrition affect hypothyroidism?

Your thyroid gland uses iodine to produce thyroid hormones.

However, if you have Hashimoto’s disease or other types of autoimmune thyroid disorders, you may be susceptible to the harmful side effects of iodine.

Eating foods that have large amounts of iodine, such as kelp, dulse or other types of seaweed, can cause or worsen hypothyroidism.

Taking iodine supplements can have the same effect.

Talk to members of your health team

about which foods to limit or avoid
whether you take iodine supplements
about any cough syrups you take because they may contain iodine

If you are pregnant, you need more iodine because the baby gets iodine from your diet. Talk to your doctor about how much iodine you need.

References

[1] Patil N, Rehman A, Jialal I. Hypothyroidism. In: StatPearls [Internet]. StatPearls Publishing; 2020. Updated August 10, 2020. Accessed January 5, 2021. www.ncbi.nlm.nih.gov/books/NBK519536 NIH external link

[2] Pearce EN, Farwell AP, Braverman LE. Thyroiditis. New England Journal of Medicine. 2003;348(26):2646–2655. doi: 10.1056/NEJMra021194. Erratum in: New England Journal of Medicine. 2003;349(6):620. www.nejm.org/doi/10.1056/NEJMra021194 External link

[3] Jonklaas J, Bianco AC, Bauer AJ, et al; American Thyroid Association Task Force on Thyroid Hormone Replacement. Guidelines for the treatment of hypothyroidism: prepared by the American Thyroid Association Task Force on Thyroid Hormone Replacement. Thyroid. 2014;24(12):1670–1751. doi: 10.1089/thy.2014.0028

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