Underactive thyroid: symptoms, cause & treatment

Symptoms of an underactive thyroid are chronic fatigue and coldness. An underactive thyroid has even more symptoms, such as unexplained weight gain (gaining weight); constipation; dry skin; slow heart rate; lower voice; muscle pain and weakness; slowness in thinking and acting; poor hair and nail growth; hair loss; changes in menstruation; poor memory and difficulty concentrating. Women who suffer from an underactive thyroid gland (or overactive thyroid gland) often have difficulty becoming pregnant. All in all, an underactive thyroid gland has far-reaching consequences. Fortunately, medications can provide relief for an underactive thyroid. The doctor usually tests for an underactive thyroid with blood tests. Many people with an underactive thyroid suffer from weight problems. What is the best way to lose weight if you have an underactive thyroid?

  • Underactive thyroid gland (hypothyroidism)
  • Causes of an underactive thyroid gland
  • Autoimmune hypothyroidism
  • Hashimoto’s disease
  • Subacute or viral thyroiditis
  • Treatment for an overactive thyroid
  • Drug-induced hypothyroidism
  • Endemic hypothyroidism
  • Congenital hypothyroidism (CHT)
  • Disorder of the pituitary gland or hypothalamus
  • Maternal hypothyroidism
  • Postpartum thyroiditis
  • Who is at risk of developing hypothyroidism?
  • Polyglandular autoimmune syndrome
  • Underactive thyroid symptoms
  • Symptoms in men and women
  • Symptoms of an underactive thyroid in babies
  • Underactive thyroid consequences
  • Diagnosis and research
  • Treatment of an underactive thyroid gland
  • Underactive thyroid gland and losing or maintaining weight
  • Prognosis
  • Complications
  • Prevention

Where is your thyroid located? / Source: Arnavaz, Wikimedia Commons (Public domain)

Underactive thyroid gland (hypothyroidism)

An underactive thyroid gland or underactive thyroid gland is called hypothyroidism . Hypo means undersized and thyroid literally means shield-shaped, which is a reference to the thyroid gland. In hypothyroidism, the thyroid gland does not produce enough thyroid hormones. However, these hormones are essential for metabolism and a deficiency irreversibly causes many bodily functions to slow down.

Hypothyroidism mainly occurs in women over the age of forty. It is seen much less commonly in men. The risk of thyroid abnormality is particularly high for women; women are eight times more likely than men to develop thyroid disease. The incidence of hypothyroidism increases significantly higher up the age ladder.

Causes of an underactive thyroid gland

Possible causes of an underactive thyroid gland are the following.

Autoimmune hypothyroidism

The cause of hypothyroidism is usually an autoimmune disease, in which your body produces antibodies against your thyroid gland. This causes cells to be destroyed and the thyroid gland to produce too little thyroid hormone. Ultimately, the thyroid gland can fail completely, meaning no more thyroid hormone is produced. Hashimoto’s disease is the most common autoimmune disease with approximately 90% (see below).

Hashimoto’s disease

This is an autoimmune disorder in which the body’s own immune system targets thyroid cells, destroying these cells and causing the thyroid gland to gradually slow down and produce less and less thyroid hormone over time. This hereditary condition is the most common cause of hypothyroidism in adults.

Subacute or viral thyroiditis

Subacute or viral thyroiditis or inflammation of the thyroid gland after a viral illness. This condition occurs regularly, sometimes in such a mild form that it is not recognized and is mistaken for the flu. Since it almost always heals naturally, there is no problem if it is not recognized.

Treatment for an overactive thyroid

Treatment for an overactive thyroid that involves radioactive iodine or surgical removal of part of the thyroid gland can lead to hypothyroidism.

Drug-induced hypothyroidism

Drug-induced hypothyroidism can occur as a result of the use of iodine-containing drugs.

Endemic hypothyroidism

Insufficient iodine in the diet, extremely rare in developed countries. Iodine is essential for the production of thyroid hormones.

Congenital hypothyroidism (CHT)

CHT is a congenital condition, in which in many cases there is an insufficient or absent development of the thyroid gland.

Pituitary gland / Source: Tefi/Shutterstock.com

Disorder of the pituitary gland or hypothalamus

A disorder of the pituitary gland or the hypothalamus, called secondary and tertiary hypothyroidism respectively. These conditions are rare. The pituitary gland and the hypothalamus play a direct and indirect role respectively in the functioning of the thyroid gland and therefore in the production of thyroid hormones. The pituitary gland secretes a thyroid-stimulating hormone (TSH). Insufficient production of this hormone can be caused by a tumor in the pituitary gland. The hypothalamus largely regulates the functioning of the pituitary gland. If this system becomes disrupted, this will have consequences for the functioning of the thyroid gland.

Maternal hypothyroidism

Some women do not produce enough extra thyroid hormone during pregnancy. This is called ‘maternal hypothyroidism’. In that case, the pregnant woman must take extra thyroid hormone (tablets with levothyroxine).

Postpartum thyroiditis

This indicates a temporary or permanent thyroid dysfunction that occurs in the first year after childbirth and is caused by destructive autoimmune thyroiditis.

Who is at risk of developing hypothyroidism?

Women, especially older women, are more likely to develop hypothyroidism than men. You’re also more likely to develop hypothyroidism if you have a close family member with an autoimmune disease. Other risk factors include:

  • Ethnic origin (European or Asian);
  • Age (the older, the more likely);
  • Having premature gray hair;
  • Autoimmune diseases such as type 1 diabetes, multiple sclerosis (MS), rheumatoid arthritis, celiac disease, Addison’s disease, pernicious anemia, or vitiligo;
  • Bipolar disorder;
  • Down syndrome; and
  • Turner syndrome, a chromosomal abnormality.

People with type 1 diabetes are more at risk of thyroid disease.
Patients with type 1 diabetes are more likely than others to develop an autoimmune thyroid disease (such as Hashimoto’s disease, an autoimmune condition in which the body makes antibodies against the thyroid gland). and thus the thyroid gland is switched off, or Graves’ disease, an autoimmune disease in which hyperthyroidism occurs). This is because the predisposition to autoimmune problems is familial (i.e. more common within a family). Type 1 diabetes is an autoimmune disease in which the body’s own immune system destroys insulin-producing cells. Although estimates vary, the risk of developing an underactive thyroid or an overactive thyroid can be as high as 30 percent in people with type 1 diabetes.[1] So people with a predisposition to a form of an autoimmune disease have an increased risk of developing, for example, Graves’ disease, but also diabetes. There is no clear relationship between type 2 diabetes and hypothyroidism. Type 2 diabetes, unlike type I, is not an autoimmune disease. A person with type 2 diabetes therefore does not have an increased risk of developing an autoimmune thyroid disease.

Vitiligo of the hands in a dark-skinned person / Source: James Heilman, MD, Wikimedia Commons (CC BY-SA-3.0)

Polyglandular autoimmune syndrome

The University Medical Center Groningen (UMCG) reports that an underactive thyroid gland sometimes does not occur alone. According to the UMCG, people with hypothyroidism are more likely to have pernicious anemia (often an autoimmune disease and one of the most common causes of a vitamin B12 deficiency), autoimmune adrenocortical insufficiency, type 1 diabetes, vitiligo (a skin disease in which certain pigment abnormalities occur), and other autoimmune conditions. This is called the ‘polyglandular autoimmune syndrome’. Therefore, in case of unexplained residual symptoms of hypothyroidism, the possibility of such a combination should be considered.[2]

Underactive thyroid symptoms

Symptoms in men and women

The severity of the symptoms varies per case. The complaints can develop over the months and go unnoticed for a long time. The symptoms and complaints of an underactive thyroid are:

  • Fatigue, even with minimal physical exertion;
  • General weakness, feeling weak;
  • Gaining weight or having difficulty losing weight;
  • Constipation or constipation (constipation);
  • Hoarse voice, deeper voice or cracking voice;
  • Hypersensitivity to cold, the person is chilly;
  • Swelling of the face (puffy face), swollen eyes and dry, puffy skin, swollen ankles (myxoedema);
  • General hair loss (of scalp hair but also of eyebrows, legs and arms);
  • Brittle hair;
  • Slow speech;
  • Irregular or heavy menstruation in women;
  • Muscle pain (stiff, painful muscles and joints especially in arms, legs, hips and hands);
  • Muscle cramps, including leg cramps;
  • Muscle weakness;

Weight gain due to an underactive thyroid / Source: Istock.com/VladimirFLoyd

  • Poor appetite;
  • Tongue tingling or tingling tongue;
  • A burning sensation, itching, tingling (as if small insects are crawling under your skin) in the arms and/or legs (or feet), usually upon waking
  • Dry skin, rough skin, cold skin or pale-yellow skin;
  • Eye swelling and facial swelling;
  • Depression;
  • Apathy, listlessness;
  • Amnesia;
  • Concentration disorders;
  • Slowed thinking and slowed mental activity – slowness in thinking and acting;
  • Confusion;
  • Increased cholesterol levels in the blood;
  • A tumor in the neck due to swelling of the thyroid gland (goiter or goitre);
  • Deafness;
  • Nervousness;
  • Emotional lability;
  • Itch;
  • Nail abnormalities:
    • Brittle, fragile nails;
    • Spoonnails (koilonychia);
    • Nail detachment (onycholysis).
  • Loss of libido: less desire for sex;
  • Fertility disorders;
  • Secretion of milk from the breast;
  • Pubertas praecox (premature puberty);
  • Slow heart rate (bradycardia).

Symptoms of an underactive thyroid in babies

Babies with hypothyroidism may not have any symptoms. If symptoms occur, they may include:

  • Cold hands and feet;
  • Constipation;
  • Extreme drowsiness;
  • Crying with a faint or hoarse sound;
  • Reduced growth;
  • Low muscle tone (hypotonia);
  • Persistent jaundice (yellowing of the skin and whites of the eyes);
  • Bad food;
  • Bloated face;
  • Bloated belly; and
  • Swollen tongue.

Underactive thyroid consequences: an underactive thyroid can cause high blood pressure / Source: Istock.com/KatarzynaBialasiewicz

Underactive thyroid consequences

As a result of an underactive thyroid gland, a variety of complaints can arise such as fatigue, dry skin, chills, slowness in thinking and acting and constipation, and, among other things, the blood cholesterol level and blood pressure rise. If you have an underactive thyroid, you are more likely to develop cardiovascular disease. The sooner such an abnormality can be diagnosed, the sooner treatment can be initiated and the consequences can be limited.

Underactive thyroid gland: consequences for the unborn child
It is known that a low level of the thyroid hormone thyroxine in the mother in early pregnancy leads to a reduced IQ of the child. Research by pediatrician-endocrinologist Martijn Finken and his team now shows that this hormone deficiency leads to poorer school performance at a young age, especially in arithmetic. The results of the study were published in the European Journal of Endocrinology .[3] Thyroxine is of cardinal importance for the development of the baby’s brain during pregnancy. During the first trimester of pregnancy, the unborn child is not able to produce this hormone itself. The child is dependent on the mother’s supply via the placenta. A low level of this hormone in the mother therefore has consequences for the child’s school performance. Follow-up research will have to show whether the developmental delay persists.

Blood collection / Source: Istock.com/anna1311

Diagnosis and research

If hypothyroidism is suspected, the GP will have blood tests carried out to determine the amount of thyroid hormones (T4 and T3), the amount of thyroid-stimulating hormone (TSH) and the amount of antibodies against the thyroid (anti-TPO).

Thyroid values
Each laboratory uses its own normal values (these are the limit values that correspond to normal functioning of the thyroid gland). These are always stated with the result. The most common values are:

Type of hormone:

Normal values:


0.4 – 4.0 mU/l


9 – 24 pmol/l


8 – 26 pmol/l


1.2 – 3.4 nmol/l


3 – 8 pmol/l

Most of the hormones T4 and T3 bind to proteins in the blood. A small part is immediately available, which is indicated by the letter F for free = free. A high free T4 and T3 (or total T4 and T3) result indicates an overactive thyroid, while a low free T4 and T3 (or total T4 and T3) is consistent with an underactive thyroid. The T4 and T3 test results may prompt the doctor to conduct additional research into the cause of the deficiency (or excess) of thyroid hormone.

Differential diagnosis
The symptoms of hypothyroidism are not specific and can be very similar to many other conditions. Therefore, the list of differential diagnoses is long:

  • anovulation (the ovaries are unable to release an egg);
  • craniopharyngioma (a benign tumor of the pituitary gland);
  • chronic megacolon (a condition in which the colon is dilated and enlarged);
  • chronic fatigue or chronic fatigue syndrome (CFS);
  • depression;
  • dysmenorrhea (painful menstruation);
  • eosinophilia (an increase in the number of eosinophils in the blood);
  • eosinophilia-myalgia syndrome (characterized by eosinophilia and severe myalgia);
  • erectile dysfunction;
  • familial hypercholesterolemia (an inherited condition in which the cholesterol level in the blood is too high);
  • fibromyalgia (a form of soft tissue rheumatism that causes pain, stiffness and fatigue);
  • geriatric sleep disorder;
  • cardiac tamponade (fluid gets between the protective membrane or sac of the heart);
  • hypercholesterolemia (a metabolic disorder in which there is too high a cholesterol level in the blood);
  • hypoalbuminemia (decreased levels of proteins in the blood);
  • hypochondria (fear of illness);
  • pituitary macroadenomas (adenomas with a diameter greater than 10 mm in the pituitary gland);
  • hypopituitarism (deficiency of one or more hormones of the pituitary gland) or panhypopituitarism (deficiency or deficiency of all hormones of the anterior pituitary gland);
  • hypothermia (hypothermia);
  • ileus (intestinal blockage);
  • iodine deficiency;
  • mononucleosis (another name is glandular fever due to swollen glands);
  • lithium nephropathy (kidney problems due to lithium);
  • menopause;
  • myxedema coma or crisis (very severe hypothyroidism);
  • constipation;
  • obstructive sleep apnea syndrome or OSAS (where the muscles relax during sleep in such a way that the tongue and soft parts in the throat block breathing);
  • infertility;
  • pericardial effusion (a collection of fluid in the pericardium);
  • primary ovarian insufficiency (early menopause);
  • prolactin deficiency (a deficiency of the hormone prolactin);
  • thyroid cancer;
  • sleep problems;
  • goiter (thyroid enlargement);
  • subacute granulomatous thyroiditis (form of thyroiditis);
  • syndrome of inappropriate antidiuretic hormone secretion or SIADH (a condition in which the pituitary gland secretes too much antidiuretic hormone into the blood);
  • thyroiditis, subacute (thyroid inflammation);
  • Riedel’s thyroiditis (certain form of inflammation of the thyroid gland);
  • thyroxine binding globulin (TBG) deficiency (TBG is a protein that binds the thyroid hormone so that it does not flow freely in the blood);
  • polyglandular autoimmune syndrome (PAIS) types I, II and III (autoimmune diseases);
  • rare tumors of the mediastinum (space in the chest located between the two lungs);
  • Addison’s disease (a rare abnormality of the adrenal glands); and
  • obesity or obesity.

Examination of the thyroid gland / Source: Istock.com/KatarzynaBialasiewicz

Treatment of an underactive thyroid gland

Synthetic thyroid hormone
Hypothyroidism is a treatable condition. Although there are several causes for hypothyroidism, the treatment is the same, namely with a synthetic thyroid hormone (levothyroxine) – a drug that the patient will have to take for life. Symptoms will improve approximately three weeks after starting treatment. The doctor will regularly check the amount of thyroid hormone in the blood and use this to determine the correct dosage. If necessary, the dosage is adjusted. Only rarely does it happen that the thyroid gland starts working again. This is possible, for example, if delayed thyroid function has occurred after pregnancy.

Determining the correct dose of hormone tablets can sometimes take months. Food reduces absorption and it is therefore recommended to take the medicine on an empty stomach: half an hour before breakfast. You can also take the hormone tablets before going to bed. Furthermore, iron salts, multivitamins with iron and calcium would reduce the absorption of the medication in the intestine. Coffee, soybean-based foods and chromium supplements also reduce absorption.

Coffee reduces the absorption of hormone tablets / Source: Istock.com/PuwanaiSomwan

Residual complaints
If (residual) complaints still exist after proper medication adjustment, it is important to investigate and rule out alternative causes. An autoimmune thyroid disorder is often secondary to other autoimmune disorders, such as diabetes type I, autoimmune adrenocortical insufficiency, pernicious anemia and/or celiac disease.

Underactive thyroid gland and losing or maintaining weight

Many people with an underactive thyroid suffer from weight problems and gain a few kilos, despite living a healthy lifestyle and exercising sufficiently. For them it is no easy feat to maintain their weight. If you have an underactive thyroid, your energy metabolism is at a lower level, which means your calorie requirement is lower than normal. If the incoming calories from food remain the same, people with a lower burn level will inevitably gain weight. However, if you are adequately adjusted and treated with thyroid hormone, this balance should be restored. However, practice shows that this does not happen to everyone and it is still unclear why this is the case.

Losing weight and keeping it off
If you gain weight while you are well adjusted to medication, losing weight is an option. You can follow a diet for this, both independently and under the guidance of a dietician. The same diet and exercise recommendations apply to people with an underactive thyroid as to people without a thyroid disorder. Therefore, do not follow a crash diet where you try to lose as many excess pounds as possible in a short time. Losing weight and reaching your target weight must be done in a gradual and responsible manner, with a healthy, varied diet and sufficient exercise every day as spearheads. Daily exercise can be a difficult task due to the fatigue and joint pain that some people with an underactive thyroid suffer. However, these complaints appear to improve if you are physically active. If necessary, do this under the supervision of a physiotherapist. The pace of increasing physical activity is different for everyone. Choose a sport or activity (for example walking or cycling) that suits you.


With adequate treatment, thyroid hormone levels often normalize again. Most people rely on medication for life.


Untreated hypothyroidism can lead to:

  • Heart problems;
  • Infertility;
  • Joint pain; and
  • Overweight or obesity.

Unborn child
Thyroid problems in a pregnant woman can affect the development of the unborn child. During the first three months of pregnancy, the baby receives all the thyroid hormones from its mother. If the mother has hypothyroidism, the child does not get enough thyroid hormone. This can lead to problems with his mental development.

Extremely low levels of thyroid hormone can lead to a life-threatening condition known as ‘myxedema’. Myxedema is the most severe form of hypothyroidism. A person with myxedema may lose consciousness or fall into a coma. The condition can also lead to a sharp drop in body temperature, which can lead to death.


Most cases of hypothyroidism in the Netherlands are caused by Hashimoto’s disease, which cannot be prevented. Although you can’t prevent hypothyroidism, you can be alert to signs of the disease so it can be treated promptly. Some people who are at high risk of developing hypothyroidism but have no symptoms may be tested to see if they have mild or subclinical hypothyroidism. One group that should be screened occasionally for an underactive thyroid are the elderly, especially women over 60 years of age, who have a family history of hypothyroidism, and those who have Addison’s disease, rheumatoid arthritis, pernicious anemia, or have type 1 diabetes.


  1. People With Type 1 Diabetes at Risk of Thyroid Disease, 15-03-2013, www.drugs.com
  2. Underactive thyroid gland, July 7, 2009, www.umcg.net
  3. VUmc. Child of mother with an underactive thyroid has poorer arithmetic skills, August 26, 2015

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