Hypothyroidism and Hyperthyroidism: What Are They and What’s the Difference?

If you’ve ever Googled about thyroid diseases, you would have inevitably come across the terms ‘hypothyroidism’ and ‘hyperthyroidism’. You’d probably have known that they are thyroid diseases, but what’s the difference between them?

Hypothyroidism and hyperthyroidism are among the most common thyroid disorders that affect millions of Americans. More than 12% of Americans will develop a thyroid disorder at some point in their lives. More disturbingly, up to 60% of an estimated 20 million Americans with thyroid diseases are not even diagnosed since thyroid diseases are notoriously tricky to pinpoint.

Since so many people are leading lives without getting their thyroid diseases diagnosed, is it really important to learn about them? Absolutely.


Your thyroid is a small butterfly-shaped gland that sits at the base of your neck. For such a small gland, your thyroid impacts your health enormously. It affects many major functions of your body like your basal metabolic rate, heart rate, your central nervous system, and much more.

Thyroid hormones travel through your bloodstream to regulate the metabolism of your cells. Other parts of your body like the pituitary gland and the hippocampus work together to signal your thyroid for thyroid hormones. It’s important that your thyroid releases just the right amount of thyroid hormones. If your thyroid hormones are imbalanced, you will experience a whole host of issues with your body.


Hypothyroidism is a thyroid disorder that slows down your thyroid hormone production. When there are not enough thyroid hormones circulating in your body, your metabolism slows down which will cause other functions of your body to slow down as well.

Some of the common symptoms of hypothyroidism include:

  • Weight gain
  • Pain or stiffness in your joints
  • Muscle aches
  • Irregular or heavy periods
  • Infertility
  • Hair loss
  • Fatigue
  • Depression or feeling low
  • Increased sensitivity to cold or chills
  • Constipation
  • Dry skin
  • Slowed heart rate
  • Impaired memory

If left untreated, you will experience a range of complications that can drastically worsen your life. 10% of women with underlying thyroid problems might experience postpartum thyroiditis, an uncommon thyroid disease that inflames a woman’s thyroid after having a baby for the first time. Most of the time, it goes away by itself. But in some cases, women develop permanent thyroid problems that they have to deal with for life. Your baby is also more likely to develop a birth defect if you don’t treat hypothyroidism on time.

You might also develop heart diseases. This is because, without the hormones needed to regulate your cholesterol, bad cholesterol builds up in your heart. Too much buildup will increase your risk of heart attack and stroke. Hypothyroidism also causes a buildup of fluids around your heart, which might make it harder for your heart to function properly.

Who Is More Likely to Be Affected By Hypothyroidism?

Hypothyroidism typically affects more women than men. You are especially more vulnerable if you are over 60, have a family history of thyroid disorders, or if you have an autoimmune disease. As a woman, you also increase your risk if you have given birth in the past six months.

Besides that, you are also more likely to get hypothyroidism if you’ve ever had a thyroid disease in the past and have received treatment for it. You also increase your risk of getting hypothyroidism if you have ever received a radioactive treatment for your neck or your upper chest.


Hyperthyroidism, also known as overactive thyroid, is a thyroid disorder that produces way too many thyroid hormones. When there are too many thyroid hormones circulating in your system, your metabolism speeds up.

Some of the common symptoms of hyperthyroidism are:

  • Increased or irregular heart rate
  • Heart palpitations
  • Unexpected weight loss
  • Tremors
  • More frequent bowel movements
  • Muscle weakness
  • Sweating
  • Nervousness
  • Low sperm count
  • Premature balding

Like hypothyroidism, you might experience a lot of complications if your hyperthyroidism is left untreated. For men, low sperm count from hyperthyroidism can cause erectile dysfunction (ED), which will severely impact your quality of life. Besides that, too many thyroid hormones in your system will also lower your testosterone. This means you might lose muscle mass, bone density, sleep quality, and experience fluctuation moods.

Speaking of mood fluctuations, up to 60% and 69% of patients diagnosed with hyperthyroidism also have anxiety and depression respectively. Some patients even experience manic episodes that need more intensive treatment for a full recovery. Some studies even recommend treating underlying thyroid imbalance before treating psychiatric symptoms since your thyroid might be the culprit behind the mood swings.

Who Is More Likely To Be Affected By Hyperthyroidism?

Women are more likely to get hyperthyroidism than men, especially if you have a family history of thyroid diseases. Besides that, you’re also more likely to be affected by hyperthyroidism if you’ve ever been affected by Grave’s Disease. Chronic illnesses like Type I diabetes and pernicious anemia also contribute to the risk factors of hyperthyroidism.

Differences Between Hypothyroidism and Hyperthyroidism

Essentially, hypothyroidism and hyperthyroidism are two different disorders that are triggered when there is a change in thyroid hormone output. If you have hypothyroidism, your thyroid hormone production is slowed down. If you have hyperthyroidism, your hormone production speeds up.

Besides that, hypothyroidism causes symptoms that slow your metabolism down like weight gain and slowed heartbeat. You’ll feel bogged down and slow if you have hypothyroidism. Hypothyroidism is also often linked with depression.

On the flip side, you might feel like you have more energy with hyperthyroidism. Hyperthyroidism speeds up your metabolism, so you’ll experience symptoms like heart palpitations, slight tremors, and increased bowel movements. In terms of mental symptoms, you might experience anxiety, depression, manic episodes, or even full-blown bipolar episodes.

Bottom Line

Hypothyroidism and hyperthyroidism are both dangerous because they tend to creep up on you and worsen as time passes. You might not think these symptoms are a big deal in the beginning. Some people won’t even think of their thyroid when they treat symptoms like feeling unmotivated, fatigue, or infertility.

Because of this, you risk misdiagnosis and treating yourself for something totally unrelated. Instead of treating your thyroid with lifestyle changes and thyroid supplements, you might stress yourself out with treatments that won’t work. Especially with the high cost of healthcare, it might be wiser to first check out your thyroid if you experience symptoms of hypothyroidism and hyperthyroidism all of a sudden.

Thankfully, both thyroid disorders are easily treatable if detected early. If you suspect your thyroid is robbing you of your right to live better, schedule a thyroid scan with your doctor as soon as possible.