Hypothyroidism is when the thyroid gland does not produce enough thyroid hormones to meet the needs of the body. The thyroid is underactive.

The opposite is hyperthyroidism, where the thyroid produces too much thyroid hormone. However, the link between hyperthyroidism and hypothyroidism is complex, and one can lead to the other, in certain circumstances.

Thyroid hormones regulate metabolism, or the way the body uses energy. If thyroxine levels are low, many of the body’s functions slow down.

The thyroid gland is found in the front of the neck below the larynx, or voice box, and has two lobes, one on each side of the windpipe.

The production of thyroid hormones is regulated by thyroid-stimulating hormone (TSH), which is made by the pituitary gland.

Symptoms

Thyroid hormones affect multiple organ systems, so the symptoms of hypothyroidism are wide-ranging and diverse.

The thyroid creates two thyroid hormones, triiodothyronine (T3) and thyroxine (T4). These regulate metabolism, and they also affect the following functions:

• brain development
• breathing
• heart and nervous system functions
• body temperature
• muscle strength
• skin dryness
• menstrual cycles
• weight
• cholesterol levels

Symptoms of hypothyroidism commonly include, but are not limited to:

• fatigue
• weight gain
• cold intolerance
• slowed heart rate, movements, and speech
• joint and muscle pain, cramps, and weakness
• constipation
• dry skin
• thin, brittle hair or fingernails
• decreased sweating
• pins and needles
• heavy periods, or menorrhagia
• weakness
• high cholesterol
• puffy face, feet, and hands
• insomnia
• balance and co-ordination issues
• loss of libido
• recurrent urinary and respiratory tract infections
• anaemia
• depression

If left untreated, the following symptoms can manifest:

• hoarseness
• puffiness in the face
• thinned or missing eyebrows
• slow heart rate
• hearing loss

If it develops in children or teenagers, the signs and symptoms are generally the same as adults.

However, they may also experience:

• poor growth
• delayed development of teeth
• poor mental development
• delayed puberty

Hypothyroidism develops slowly. Symptoms may go unnoticed for a long time, and they may be vague and general.

Symptoms vary a great deal between individuals, and they are shared by other conditions. The only way to obtain a concrete diagnosis is through a blood test.

Treatment

Treatment for hypothyroidism focuses on supplementing the thyroid hormone. At present, doctors cannot cure hypothyroidism but they can help people to control it in most cases.

Synthetic thyroxine

To replenish levels, doctors usually prescribe synthetic thyroxine, a medication that is identical to the T4 hormone. Doctors may recommend taking this in the morning before eating each day.

Dosage is determined by the patient’s history, symptoms, and current TSH level. Doctors will regularly monitor the patient’s blood to determine if the dosage of synthetic T4 needs to be adjusted.

Regular monitoring will be required, but the frequency of blood tests will likely decrease over time.

Iodine and nutrition

Iodine is an essential mineral for thyroid function. Iodine deficiency is one of the most common causes of goiter development, or abnormal enlargement of the thyroid gland.

Maintaining adequate iodine intake is important for most people, but those with autoimmune thyroid disease can be particularly sensitive to the effects of iodine, meaning that it can trigger or worsen hypothyroidism.

They should inform their doctor if they are sensitive to the effects of iodine.

People with hypothyroidism should discuss any major dietary changes with their doctor, especially when starting a high fiber diet, or eating lots of soy or cruciferous vegetables.

Diet can affect the way in which the body absorbs thyroid medication.

During pregnancy, iodine requirements increase. Using iodized salt in the diet and taking prenatal vitamins can maintain the required levels of iodine.

Iodine supplements are available for purchase online.

Hypothyroidism can normally be managed appropriately by following the advice of a qualified healthcare practitioner. With appropriate treatment, thyroid hormone levels should return to normal.

In most cases, medications for hypothyroidism will need to be taken for the rest of the patient’s life.