What is hypothyroidism?

If you ever feel tired, lethargic, or depressed, you could be suffering from hypothyroidism.

Hypothyroidism is a condition in which the thyroid gland is unable to produce or release enough thyroid hormones. Incidences of hypothyroidism increases with age.

Approximately 4.6% of the American population¹ age 12 years and over suffers from it although 1 in every 4- 5 million babies born in the US have congenital hypothyroidism.

The main cause of hypothyroidism is believed to be hereditary, although iodine deficiency can also lead to hypothyroidism. It is also much more common in women than men².

Role of the thyroid gland

To understand what is hypothyroidism, we need to understand the role of the thyroid gland and how it works. The thyroid gland³ is a small butterfly shaped gland located at the base of the front of the neck. This gland is responsible for regulating the body’s metabolism.

Metabolism refers to all of the chemical reactions which take place in the body such as the breaking down of food to release energy, or the building of new nutrients such as proteins and nucleic acids which are essential for your body to work properly. If any of these processes are affected, the sufferer may experience a wide range of symptoms including fatigue, weight gain, hair loss, and depression.

Hypothyroidism is caused by a lack of T3 (Triiodothyronine) and Thyroxine (T4)—the two main hormones produced by the thyroid gland. Production of these hormones is regulated by a third hormone, TSH (Thyroid Stimulating Hormone) which is produced by the pituitary gland⁴ in the brain. This in turn is controlled by a fourth hormone, Thyrotropin-releasing hormone (TRH) which is secreted by the hypothalamus.

Essentially, TRH from the hypothalamus stimulates production of TSH from the pituitary gland. TSH stimulates the thyroid gland which produces mostly T4. T3 is then formed through the conversion of T4. The levels of TRH and TSH are controlled by the blood levels of T3 and T4.

In short, hypothyroidism may occur when there is a problem in the functioning of any of these areas: the hypothalamus, pituitary gland, or thyroid gland.

How do you know if you have hypothyroidism?

Early hypothyroidism may not cause noticeable symptoms. But over time, untreated hypothyroidism can lead to a wide range of symptoms such as weight gain, hair loss, cold intolerance, constipation, mental slowing, muscle weakness, menstrual abnormalities, and depression.

A more comprehensive list of symptoms is provided further on in this article.

What causes hypothyroidism?

Hypothyroidism is most commonly caused by autoimmune hypothyroidism (Hashimoto’s thyroiditis⁵) in the US. However, inadequate iodine intake is the most common cause of hypothyroidism worldwide because of a lack of dietary iodine.

Hashimoto’s thyroiditis occurs when the body attacks its own thyroid gland. Over time, the thyroid gland is gradually destroyed and may become enlarged. Thyroid enlargement or goiter can also be caused by other conditions like hyperthyroidism.

Other causes of hypothyroidism include:

• Dietary iodine deficiency
• Tumors
• Inflammatory disorders of the hypothalamus or pituitary gland
• Medications (lithium, amiodarone)
• Radiation therapy to the head and neck
• Thyroid surgery
• Lack of conversion from T4 to T3
• An inability to absorb thyroxine properly
• Environmental conditions- some foods, drinks and chemicals can cause problems for the thyroid gland
• Problems with the pituitary gland or hypothalamus
• A genetic predisposition- the thyroid may be dysfunctional at birth or be pre-programmed genetically to malfunction later in life.
• Other inherited diseases such as type 1 diabetes, Addison’s disease and rheumatoid arthritis may also increase the likelihood of developing hypothyroidism.

Subclinical or borderline hypothyroidism

If a patient produces too much TSH but their levels of T3 and T4 are normal, this is referred to as subclinical or borderline hypothyroidism. The symptoms of this may go unnoticed.

There is disagreement among providers about whether to treat subclinical hypothyroidism⁶. Many sufferers find that their levels of TSH return to normal within a year without clinical intervention and only 3% go on to develop the classical form of hypothyroidism.

Congenital hypothyroidism (CH)

If a baby is born with hypothyroidism, this is referred to as congenital hypothyroidism⁷ (CH).

All babies are checked for CH during routine newborn screening. Approximately 1,400 babies per 5,000,000 are diagnosed with congenital hypothyroidism each year. This means that their thyroid gland is absent or severely deficient. This condition must be treated early in order to avoid irreversible neurological problems and poor growth.

Children who develop hypothyroidism after birth have what is called primary hypothyroidism. These children do not usually experience the same neurological problems as those with CH. But again, as in all cases, early diagnosis and treatment is important.

Hypothyroidism symptoms

Hypothyroidism symptoms can be extremely difficult to diagnose, particularly in its early stages. Generic symptoms such as memory loss, depression or a slower growth rate are all classic hypothyroidism symptoms which can go unnoticed.

This is because the symptoms of hypothyroidism usually develop slowly and gradually increase over many years. It’s also easy to dismiss the condition or explain the symptoms away as being something else.

There are a huge range of hypothyroidism symptoms⁸ which are summarized in the following non-exhaustive list. Seek medical advice if you have any suspicious symptoms (even if they are not listed here).

Physical symptoms of hypothyroidism

• Excessive tiredness, muscle weakness or cramps
• Weight gain
• Loss of hair to the body and head, including eyelashes. Hair may be brittle or thin.
• Slow movements including Achilles reflex and speech
• Pins and needles
• Breathlessness and palpitations
• Liver may become sore and enlarged
• Insomnia
• Loss of libido
• Candida
• Pelvic Inflammatory disease
• Repeated urinary infections or protein in urea (Albuminuria)
• Upper respiratory tract infections
• Low body temperature, intolerance to hot or cold temperatures.
• Numbness or puffiness to hands, feet or ankles
• Skin conditions such as dryness, eczema or psoriasis
• Difficulty swallowing, a swollen tongue or throat
• High or low blood pressure
• Migraines, headaches, or dizziness
• Digestive problems such as constipation, haemorrhoids, Irritable Bowel Syndrome (IBS), or abdominal distension
• Menstrual disorders: PMT; periods may stop or become irregular/heavy
• Problems with sight or hearing difficulties
• Poor growth and neurological problems in children born with CH

Mental and emotional symptoms of hypothyroidism

The following mental symptoms may also indicate hypothyroidism (for physical conditions, consider seeking advice from a medical professional):

• Panic attacks, memory loss, and confusion
• Mental sluggishness and poor concentration
• Personality changes, phobias, noises in head
• Mood swings, feelings of resentment
• Lack of confidence, easily upset, wanting to be alone
• Anxiety or nervousness
• Depression

Congenital and primary hypothyroidism

If a child develops hypothyroidism after birth, this is referred to as primary hypothyroidism. For either condition, it’s important to seek immediate treatment in order to avoid problems with mental development, learning difficulties and poor growth.

Symptoms of congenital hypothyroidism

If your baby is unresponsive, constipated, has difficulty feeding, or doesn’t cry very much and also shows any of the following symptoms then this may indicate hypothyroidism:

• Puffy appearance
• Broad, flattened nose
• A swollen enlarged tongue
• Large soft spots on the skull.
• Umbilical hernia: where part of the bowel or fatty tissues pushes through the abdominal wall near the belly button
• Weak and floppy muscles
• Enlarged heart, a slow heart rate, or fluid around the heart
• Goiter: a swelling of the neck caused by the enlargement of the thyroid gland.
• Jaundice: this is where the skin or the whites of the eyes appear yellow due to high levels of bilirubin. This is fairly common in babies following birth but it can be an indicator of other conditions, such as thyroid problems or liver disease.

What are the symptoms of primary hypothyroidism?

Older children with hypothyroidism may be short, have swollen eyelids, narrow palpebral fissures⁹, and higher-than-normal distance between the eyes (hypertelorism¹⁰).

If you are concerned that your child may have issues with his or her thyroid gland, do err on the side of caution and seek medical attention as soon as possible.