hypothyroid
Low thyroid hormone levels result in a sluggish metabolism, which can appear in the following symptoms of hypothyroidism.

A person with hypothyroidism has low thyroid hormone levels (T3 and T4) in their blood. The symptoms of hypothyroidism may vary depending on the severity of thyroid hormone deficiency.

  • Many people may not have any symptoms or have mild or vague symptoms that often go ignored.
  • Some people may develop swelling in front of the neck due to an enlarged thyroid gland (goiter).

Low thyroid hormone levels result in a sluggish metabolism, thus a person with hypothyroidism may have:

What is hypothyroidism?

Hypothyroidism refers to low thyroid hormone levels in the body. About 5 in 100 people in the United States have been diagnosed with hypothyroidism. Because many people with this condition have no or minimal symptoms, the actual number of people living with hypothyroidism may even be higher.

The thyroid gland is a butterfly-shaped gland present in the front of the neck, just below Adam’s apple, also called the thyroid cartilage. The gland has two major types of cells: follicular and parafollicular cells (also called C-cells).

  • The parafollicular or C-cells produce the hormone calcitonin that regulates calcium utilization by the body.
  • The follicular cells produce hormones called thyroxine (T4) and triiodothyronine (T3). 
  • These hormones regulate metabolism, heart rate, body temperature, blood lipid levels, bone health, and blood pressure.
  • They are crucial for fetal growth and neuronal development. Thyroid hormones play a major role in sexual and brain development.

The release of thyroid hormones is regulated by another hormone called thyroid-stimulating hormone or TSH produced by the pituitary gland. This gland is located in the skull underneath the brain and is further regulated by a part of the brain called the hypothalamus. The hypothalamus secretes the hormone called thyroid-stimulating hormone-releasing hormone (TSH-RH), which stimulates the pituitary to release TSH.

SLIDESHOW

Hyperthyroidism: Symptoms, Treatment, Medication See Slideshow

What causes hypothyroidism?

Hypothyroidism may be caused by conditions affecting the thyroid gland, pituitary, or hypothalamus. When hypothyroidism occurs due to conditions affecting the thyroid gland, it is called primary hypothyroidism.

The causes of primary hypothyroidism include:

  • Hashimoto’s disease (the most common cause of hypothyroidism)
  • Radioiodine therapy
  • Surgical removal of the thyroid gland
  • Thyroiditis (inflammation of the thyroid gland)
  • Radiation therapy
  • Certain medications (such as antithyroid drugs used to treat hyperthyroidism)
  • Congenital hypothyroidism (hypothyroidism presence since birth due to an underdeveloped or malfunctioning thyroid gland)
  • Iodine-deficient diet (because iodine is needed for the thyroid hormone formation)

If hypothyroidism occurs due to conditions affecting the hypothalamus or pituitary gland, it is called secondary hypothyroidism. Sometimes, the term tertiary hypothyroidism is used for hypothyroidism due to conditions of the hypothalamus that affect the thyroid gland.

How is hypothyroidism diagnosed?

Hypothyroidism is diagnosed by doctors based on:

  • Medical history: The doctor may ask the symptoms you have, whether you are on any medications (including thyroid medications) or other people in your family have any thyroid or autoimmune condition, underwent any surgery, or have any history of radiation exposure in the head and neck region.
  • Physical examination: The doctor will perform a detailed physical examination, especially the examination of the neck to look for any swelling or enlarged thyroid gland. They will examine other parts of the body, including your skin, eyes, hair, nails, and chest.
  • Investigations: The doctor may order blood tests to know the levels of thyroid hormones, blood counts, and certain antibodies (raised in Hashimoto’s disease). They may order imaging tests, such as ultrasound of the neck, thyroid scan, or radioactive iodine uptake studies.

How do they treat hypothyroidism?

The treatment of hypothyroidism mainly involves thyroid hormone replacement therapy. Depending on the severity of hypothyroidism, your doctor will adjust your thyroid hormone (levothyroxine) dosages.

  • Levothyroxine should be taken on an empty stomach in the morning, about 30 to 60 minutes before having meals. The medication is preferably taken at the same time every day.
  • Certain medications, such as mineral supplements (including iron, calcium), antacids, a high fiber diet, and soy products, may interfere with levothyroxine absorption.
  • You may give a gap of at least two to four hours between any such foods or supplements and levothyroxine.
  • If you take levothyroxine at bedtime, ensure that you give a gap of at least 4 hours between your last snack or meal and your thyroid medication.

If certain medications are causing hypothyroidism, your doctor may prescribe replacements or adjust their dosages. Do not stop taking any medications without consulting your doctor.

If the goiter is significantly enlarged and causing discomfort, your doctor may suggest surgery.

Hypothyroidism can be generally well-managed with medications. One must adhere to the treatment and go for regular follow-up with their doctor. It is important because your doctor may adjust the medication dosages and timely diagnose any complications that may occur.

Certain conditions, such as pregnancy, surgery, or heart conditions, may require dose adjustments that can be done through regular follow-ups. Pregnant women often need higher dosages of thyroid hormone because the baby is dependent on the mother for its iodine needs.

What happens if you leave your hypothyroidism untreated?

If hypothyroidism is left untreated, it may progress to cause a severe and potentially fatal condition called myxedema coma. It may present as low body temperature (hypothermia) and loss of consciousness.

A myxedema coma may be triggered by infections, cold exposure, injuries, or certain medications (such as certain heart medications, lithium, and cancer medications).

Untreated hypothyroidism can lead to very low hemoglobin levels (anemia) and even heart failure. In some cases, it may lead to infertility, poor memory, and mood disorders.

QUESTION

Where is the thyroid gland located? See Answer

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Medically Reviewed on 2/14/2022
References
Image Source: iStock Images

Drugs.com. Drug Interactions between Iron Sulfate and levothyroxine. https://www.drugs.com/drug-interactions/iron-sulfate-with-levothyroxine-1082-13326-1463-0.html

National Institutes of Health. Hypothyroidism (Underactive Thyroid). https://www.niddk.nih.gov/health-information/endocrine-diseases/hypothyroidism

Ross DS. Patient education: Hypothyroidism (underactive thyroid) (Beyond the Basics). UpToDate. https://www.uptodate.com/contents/hypothyroidism-underactive-thyroid-beyond-the-basics#H15