What is hypothyroidism?
The thyroid is a gland located at the front of your neck. It produces thyroid hormones that affect nearly every process in your body. One of its most important functions involves how your body uses energy, which even impacts how fast and well your heart beats.
Women are more likely to develop hypothyroidism than men, but men may still have the disease.
Symptoms of hypothyroidism
The progression of hypothyroidism symptoms is similar to other diseases. They may develop slowly over years and become worse with time. Hypothyroidism symptoms include:
- Dry, thinning hair
- Brittle hair and nails
- Pale, dry skin
- Weight gain
- Heavy or irregular periods
- Intolerance to cold
- Less sweating than usual
- Slow movements and thoughts
- Low libido
- Joint and muscle pain
- Fertility problems
- Hoarse voice
Causes of hypothyroidism
Hypothyroidism has several causes, including:
Hashimoto’s disease is the most common cause of hypothyroidism. This is an autoimmune disease where your immune system registers the thyroid as foreign tissue and attacks it. The result is inflammation and damage in the thyroid and not enough hormones. Researchers still aren’t sure what causes Hashimoto’s disease though viruses, stress, and environmental and genetic factors may play a role. Hashimoto’s disease runs in families.
Surgical removal of the thyroid
Sometimes part or all of the thyroid is removed. This may be part of treatment for hyperthyroidism, thyroid cancer, thyroid nodules, or a large goiter. The thyroid may still produce enough thyroxine in partial removal, but total thyroid removal will cause hypothyroidism as there is no longer a thyroid to produce hormones.
Sometimes babies are born with a thyroid that doesn’t function properly. This causes hypothyroidism, which is serious in children. If left untreated, it can cause growth and development problems, improper brain development, and intellectual disability. Doctors test babies for congenital hypothyroidism at birth, however it is an uncommon condition.
Thyroid radiation treatment
Sometimes the thyroid produces too much hormone, called hyperthyroidism, which slowly damages thyroid cells. People may receive radioactive iodine treatment for this condition, which eventually destroys all the thyroid tissue and stops it from producing hormones. This eventually causes hypothyroidism.
Thyroiditis is inflammation of the thyroid. This can be caused by a viral or bacterial infection, called subacute thyroiditis. It can also develop after a woman gives birth, which is called postpartum thyroiditis.
The inflammation causes hormones stored in the gland to leak into the body. The leaking will first create a surge of hormones in the blood, which leads to hyperthyroidism. With these high levels in the blood, the thyroid will respond by not producing as much thyroxine hormone, which may lead to hypothyroidism.
Hypothyroidism can be a side effect of some medications. These include:
- Lithium for bipolar disorder treatment
- Interferon alpha for cancer treatment
- Interleukin-2 for kidney cancer treatment
- Amiodarone for heart disease treatment
When to see the doctor for hypothyroidism
It’s important to diagnose an underactive thyroid right away. Untreated hypothyroidism can lead to heart disease, nerve damage, and obesity. It can cause problems in brain development and growth in children, and birth defects, premature birth, anemia, and more during pregnancy.
Severe cases of untreated hypothyroidism, or hypothyroidism that doesn’t respond to treatment, can lead to a myxedema coma. This a life-threatening condition that causes hypothermia, confusion, and drowsiness and needs emergency treatment.
Tests for hypothyroidism
Your doctor will perform a number of tests to determine if you have hypothyroidism. These may include:
Your doctor will do tests to determine thyroid hormone levels in your blood. They will test for thyroid stimulating hormone (TSH), thyroid antibodies (anti-TPO), thyroxine (T4), and may test triiodothyronine (T3).
Physical exam and ultrasound
Your doctor may physically examine your thyroid to see if there is any inflammation, swelling, nodules, or goiter. They may do an ultrasound to check for damage to the gland.
Treatments for hypothyroidism
While there isn’t a cure for hypothyroidism, it can be treated with medication. Your doctor will likely prescribe levothyroxine to supplement your thyroid stimulating hormone. Your prescription will likely start at a low dose, which your doctor will then incrementally increase to the right amount for you. You will need to take this medication on an empty stomach in the morning about an hour before eating.
Hypothyroidism can usually be controlled with your medication. However, if there is an underlying disease like Hashimoto’s disease or thyroiditis caused by an infection, your doctor may want to include other treatments.
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Merck Manuals: "Hypothyroidism – Endocrine and Metabolic Disorders."
National Health Service: "Underactive thyroid (hypothyroidism) – Complications."
National Health Service: "Underactive thyroid (hypothyroidism) – Symptoms."
National Health Service: "Underactive thyroid (hypothyroidism) – Treatment."
National Institute of Diabetes and Digestive and Kidney Diseases: "Hashimoto's Disease."
National Institute of Diabetes and Digestive and Kidney Diseases: "Hypothyroidism (Underactive Thyroid)."
Office on Women's Health: "Thyroid disease."