Hypothyroidism: Causes, Symptoms, and Treatment

Medically reviewed by Achuta Uppu, MD, Internal Medicine. Last reviewed: October 23, 2026.

What kind of doctor treats Hypothyroidism?

An endocrinologist, a doctor who treats hormone and gland problems, often treats hypothyroidism. A primary care doctor can also check for it and start the care. A direct primary care or concierge doctor can be a first stop for an evaluation and can refer you to a specialist when needed.

What is hypothyroidism?

Hypothyroidism, also called underactive thyroid, happens when your thyroid gland does not make enough thyroid hormones to meet your body's needs. The thyroid is a small, butterfly-shaped gland in the front of your neck. Thyroid hormones control the way your body uses energy. Without enough thyroid hormones, many of your body's functions slow down. Nearly 5 out of 100 Americans ages 12 years and older have hypothyroidism, although most cases are mild or have few obvious symptoms.

Symptoms

The symptoms of hypothyroidism can vary from person to person. Common symptoms include:

  • Fatigue.
  • Weight gain.
  • Trouble tolerating cold.
  • Joint and muscle pain.
  • Dry skin and dry, thinning hair.
  • Heavy or irregular menstrual periods, or fertility problems in women.
  • Depression.
  • A slowed heart rate.
  • Goiter, an enlarged thyroid that may cause your neck to look swollen.

Hypothyroidism develops slowly, so many people do not notice symptoms for months or even years. Fatigue and weight gain are common and do not necessarily mean you have a thyroid problem. Hypothyroidism can contribute to high cholesterol. During pregnancy, it can cause complications such as premature birth, high blood pressure in pregnancy, and miscarriage.

Causes and who gets it

Hashimoto's disease is the most common cause of hypothyroidism. It is an autoimmune disorder, which means your immune system attacks your thyroid. The thyroid becomes inflamed and cannot make enough thyroid hormones. Thyroiditis, which is inflammation of the thyroid, is another cause. Some babies are born with hypothyroidism, which is called congenital hypothyroidism. Surgery to remove part or all of the thyroid can cause it. Removing the entire thyroid always results in hypothyroidism. Less often, too much or too little iodine in the diet is the cause. Disorders of the pituitary gland or hypothalamus can also be the cause.

Women are much more likely than men to develop hypothyroidism. It is also more common among people older than age 60. Other health problems linked to it include celiac disease, type 1 or type 2 diabetes, rheumatoid arthritis, and lupus.

How doctors diagnose it

A diagnosis cannot be based on symptoms alone. Many of the symptoms are the same as those of other diseases. Your doctor takes your medical history and does a physical exam. Your doctor may also use thyroid blood tests and imaging tests. These help confirm the diagnosis and find the cause. The blood tests include TSH, T3, T4, and thyroid antibody tests. If you have high cholesterol, you should get tested for hypothyroidism.

Treatment

Hypothyroidism is treated by replacing the hormones that your own thyroid can no longer make. You will take levothyroxine, a thyroid hormone medicine identical to a hormone a healthy thyroid makes. You will get a blood test about 6 to 8 weeks after you start the medicine. Your doctor will adjust your dose if needed. Hypothyroidism can most likely be fully controlled with thyroid hormone medicine. You must take it as instructed. Never stop taking your medicine without talking with your doctor first. Taking too much thyroid hormone medicine can cause serious problems, such as atrial fibrillation or osteoporosis.

When to see a doctor

Rarely, severe untreated hypothyroidism may lead to myxedema coma. In this extreme form of hypothyroidism, the body's functions slow to a life-threatening point. Myxedema coma requires immediate medical treatment. Call 911 or go to the emergency room if you have trouble breathing, faint, or have a sudden change in mental state. Symptoms alone cannot confirm a thyroid problem, so ask a doctor about a blood test.

How a direct primary care or concierge doctor fits in

A direct primary care doctor charges a flat monthly fee instead of billing insurance, while a concierge doctor usually charges more and often works alongside insurance. Either kind of doctor can order the blood tests used to check your thyroid hormone level and adjust your medicine. They can also refer you to an endocrinologist when needed.

Common questions

What is the most common cause of hypothyroidism?

The most common cause is Hashimoto's disease, an autoimmune disorder in which your immune system attacks your thyroid. The thyroid becomes inflamed and cannot make enough thyroid hormones.

How often will I need blood tests?

You will get a blood test about 6 to 8 weeks after you start the medicine. Each time your dose is adjusted, you will have another blood test. Once you have reached a dose that works, your doctor will probably repeat the blood test in 6 months and then once a year.

Can hypothyroidism be controlled with medicine?

In most cases, yes, as long as you take the medicine as instructed. Never stop taking your medicine without talking with your doctor first.

Can hypothyroidism affect pregnancy?

Yes, left untreated, hypothyroidism during pregnancy can affect both mother and baby. Thyroid medicines can help prevent problems and are safe to take during pregnancy.

Sources

  1. MedlinePlus - Hypothyroidism
  2. National Institute of Diabetes and Digestive and Kidney Diseases - Hypothyroidism (Underactive Thyroid)

Medical Disclaimer

This content is for general educational and informational purposes only and is not medical advice. It is not a substitute for professional medical advice, diagnosis, or treatment, and reading it does not create a doctor-patient relationship. Always seek the advice of your physician or another qualified health provider with any questions about a medical condition, and never disregard or delay seeking professional advice because of something you read here. If you think you may have a medical emergency, call 911 (or your local emergency number) immediately.