Hyperthyroidism (overactive thyroid) occurs when your thyroid gland produces too much of the hormone thyroxine whereas hypothyroidism occurs when your thyroid gland does not produce enough of certain important hormones.

Hyperthyroidism can accelerate your body's metabolism, causing unintentional weight loss and a rapid or irregular heartbeat but in hypothyroidism, because your thyroid gland does not produce enough hormones, your body makes less energy, and your metabolism becomes sluggish (slow).

Hypothyroidism (underactive thyroid gland) is a fairly common condition and about 5% of Indians of all ages have this condition. Hypothyroidism gets more common with age. Individuals over 60 years of age experience it more frequently. 

Women are more likely to have an underactive thyroid gland. In fact, one out of eight women will develop hypothyroidism as pregnancy, and menopause puts them at a higher risk.

Other factors such as lack of nutrition, lack of exercise, and stress play a huge role in thyroid disorders. 

Hyperthyroidism occurs when the thyroid makes too much T4, T3, or both. Hyperthyroidism is a rare but more severe condition compared to hypothyroidism. 1 out of 100 individuals is affected by hyperthyroidism. 

Let’s Understand How Hyper and Hypothyroidism Occurs

The thyroid is a small, butterfly-shaped gland located at the front of your neck. It produces tetraiodothyronine (T4) and triiodothyronine (T3), which are two primary hormones that control how your cells use energy. Your thyroid gland regulates your metabolism through the release of these hormones.

 If too many of the thyroid hormones are secreted, the body cells work faster than normal, and you have hyperthyroidism. 

If you become hyperthyroid the increased activity of your body cells or body organs may lead to a quickening of your heart rate or increased activity of your intestine can led to frequent bowel motions or even diarrhea.

On the other hand, if too few of the thyroid hormones are produced (known as hypothyroidism), the cells and organs of your body slow down. If you become hypothyroid, your heart rate, for example, maybe slower than normal and your intestines work sluggishly, so you become constipated.

The most common difference between the two diseases is related to hormone levels. Hypothyroidism leads to a decrease in hormones, whereas, hyperthyroidism leads to an increase in hormone production, and their causes are listed below.

Causes of Hypothyroidism

Hypothyroidism may be due to a number of factors, including:

  • Iodine deficiency. This trace mineral is primarily found in seafood, seaweed, plants that are grown in iodine-rich soil, and iodized salt. It is essential for the production of thyroid hormones; hence, less iodine can lead to hypothyroidism.

  • Hashimoto's Thyroiditis is an autoimmune (a condition in which your immune system mistakenly attacks your body) condition which attacks your thyroid gland and causes inflammation of your thyroid gland.

  • Damage to the pituitary gland. The pituitary gland is a small pea-sized gland that plays a major role in regulating vital body functions and general wellbeing.

  • Surgical removal of your thyroid gland.    

  • Congenital (by birth) thyroid defects.     

  • Stress. The impact of stress on the thyroid occurs by slowing your body's metabolism.

  • Pregnancy. Some women develop hypothyroidism during or after pregnancy (postpartum hypothyroidism), often because they produce antibodies (protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses) to their own thyroid gland.

Causes of Hyperthyroidism

This may occur for a number of reasons, including:

  • Graves' disease. Graves' disease is an autoimmune disorder in which antibodies produced by your immune system stimulate your thyroid to produce too much T4. It's the most common cause of hyperthyroidism.

  • Hyperfunctioning thyroid nodules (toxic adenoma, toxic multinodular goiter, or Plummer's disease).  An adenoma is a part of the gland that has walled itself off from the rest of the gland, forming non cancerous (benign) lumps that may cause an enlargement of the thyroid.

  • Thyroiditis. Sometimes your thyroid gland can become inflamed after pregnancy, due to an autoimmune condition or for unknown reasons. The inflammation can cause excess thyroid hormone stored in the gland to leak into your bloodstream. Some types of thyroiditis may cause pain, while others are painless.

Signs and Symptoms of Hypothyroidism

Usually, the symptoms of hypothyroidism are difficult to identify. 

Early symptoms can include weight gain and fatigue (feeling of tiredness). Both become more common as you age, regardless of your thyroid’s health. You may not realize that these changes are related to your thyroid until more symptoms appear. Other symptoms include:

  •  Swelling all over your body     

  •  Constipation 

  •  Hair loss, dry skin    

  •  Feeling cold        

  •  Irregular menses and/or heavy menstrual bleeding or impaired fertility

  •  Shortness of breath, hoarseness of voice

  •  Poor memory, lack of concentration, mood swings    

  •  Carpal Tunnel Syndrome (numbness and tingling in the hand and arm caused by a pinched nerve in the wrist)

In most cases, your symptoms progress gradually over the years. 

Signs and Symptoms of Hyperthyroidism

Hyperthyroidism can present with an enlarged thyroid gland (goiter), which may appear as a swelling at the base of your neck with unintentional weight loss, even when your appetite and food intake stay the same or increase. Other accompanying symptoms may be:

  • Rapid heartbeat (tachycardia), irregular heartbeat (arrhythmia), pounding of your heart (palpitations)

  • Nervousness, anxiety, and irritability

  • Trembling in your hands and fingers, sweating, and increased sensitivity to heat

  • Changes in menstrual patterns

  • Changes in bowel patterns, especially more frequent bowel movements

  • Fatigue, muscle weakness

  • Difficulty sleeping

  • Skin thinning and hair thinning 

Who Are at Higher Risk for Hypothyroidism

Hypothyroidism and hyperthyroidism can happen to anyone and their risk factors also differ from each other. 

Hypothyroidism can happen to anyone, however, you are at higher risk if you:

  • Are a woman

  • Are older than 60 years of age

  • Have a family history of thyroid disease

  • Have an autoimmune disease

  • Have been treated with antithyroid medications

  • Have had thyroid surgery

  • Have been pregnant or delivered a baby within the past six months

Who Are at Higher Risk for Hyperthyroidism

  • A family history, particularly of Graves' disease

  • Female sex

  • A personal history of certain chronic illnesses, such as type 1 diabetes, pernicious anemia, and primary adrenal insufficiency.

Hypothyroidism and hyperthyroidism are usually life-long medical conditions that need to be managed constantly. This often involves a daily medication. Your doctor will monitor your treatments and make adjustments over time. It may take some time to find the right treatment option for you and control your hormone levels, however, you can usually live a normal life.



1. Piedmont.org. 2021. Hypothyroidism and Hyperthyroidism Difference | Piedmont Healthcare. [online] Available at: <https://www.piedmont.org/living-better/the-difference-between-hypothyroidism-and-hyperthyroidism> [Accessed 4 March 2021].

2. 2021. [online] Available at: <https://www.thyroid.org/hyperthyroidism/> [Accessed 4 March 2021].


Disclaimer: This article is written by Practo for informational and educational purposes only. The content presented on this page should not be considered as a substitute for medical expertise. Please "DO NOT SELF-MEDICATE" and seek professional help regarding any health conditions or concerns. Practo will not be responsible for any act or omission arising from the interpretation of the content present on this page.