Difference Between Hypothyroidism and Hyperthyroidism?

Hyperthyroidism and hyperthyroidism are two thyroid disorders. Before we dive into “what is the difference between hypothyroidism and hyperthyroidism?” or the causes of these disorders, let’s learn about the “thyroid gland.”

The thyroid gland is the largest endocrine gland located in the neck. It is a bilobed, butterfly-shaped gland located in the neck. The gland contains thyroid follicles responsible for the release of thyroid hormones.

Outside thyroid follicles, parafollicular cells or C-cells are present, which secrete another hormone called Thyrocalcitonin (TCT), which is hypocalcemic in nature; it reduces the calcium in the blood by depositing calcium on bones. It is also hypophosphatemic, which means it reduces phosphate in the blood.

Thyroid hormones are of two types:

  • T3: triiodothyronine
  • T4: tetraiodothyronine/ thyroxine

The imbalances in the thyroid function and hence in the thyroid hormones (T3 and T4) (too little or too much thyroid hormone) are responsible for the conditions such as hypothyroidism and hyperthyroidism.

T3 is more active than T4, but T3 is produced in less amount. T4 converts to T3 by losing one iodine in tissues such as the kidney and liver.

But before we get deep into “what is the difference between hypothyroidism and hyperthyroidism?”, we need to learn about the functions of thyroid hormones first (particularly thyroxine- which is a heat production hormone):

  • It maintains basal metabolic rate (BMR)
  • It has a calorigenic effect that is the production of heat
  • Supports physical and mental growth
  • It promotes erythropoiesis (formation of RBC)
  • It plays a crucial role in most bodily functions
  • Maintains carbohydrate, protein, and fat metabolism
  • Maintains salt and water balance that is osmoregulation
  • The efficiency of growth hormone increases in the presence of thyroxine
  • It also influences the function of epinephrine and norepinephrine

What Your Thyroid Gland Does – The Basics

What is the difference between hypothyroidism and hyperthyroidism?: About Hypothyroidism and Hyperthyroidism

Hypothyroidism and hyperthyroidism are the two most common types of thyroid disorders and are very different from each other. The simple meaning of the word hypo and hyper can alone solve your question: “what is the difference between hypothyroidism and hyperthyroidism?”


Hypothyroidism (underactive thyroid) is a condition in which your thyroid gland doesn’t produce enough thyroid hormone, leading to dysfunction in various body systems.


Hypothyroidism (overactive thyroid) occurs when your thyroid gland thyroid hormones in more than the required amount. That is, it produces too much thyroid hormone. Too much hormone hence leads to various problems.

       What is the Difference Between Hypothyroidism and Hyperthyroidism?: Reasons For Respective Diseases


It may be due to several reasons. The reasons include decreased THS (thyroid-stimulating hormone) stimulation, hypoactivity of acinar cells of the thyroid gland, decreased iodine (I2) intake in the diet. Certain medications may also trigger hypothyroidism.

Other than that, some pregnant women develop hypothyroidism after giving birth (known as postpartum thyroiditis). The reason is: pregnancy is known to trigger the body to start producing thyroid gland antibodies.


Hyperthyroidism occurs due to thyroid gland cancer and is characterized by increased secretion of thyroxine and causes exophthalmic goiter. It can also be caused by several conditions, including Graves disease, Plummer’s disease, and thyroiditis.

What is the Difference between Hypothyroidism and Hyperthyroidism?: Symptoms

Although the two types of thyroid disease have very distinct symptoms, some of the symptoms, like enlargement of the thyroid gland (goiter), can overlap in both types of thyroid disease.

Here is given some of the differences in the symptoms under, “what is the difference between hypothyroidism and hyperthyroidism?”:

Symptoms of Hypothyroidism:

There are a number of hypothyroidism symptoms. The symptoms of hypothyroidism vary, depending on how severe the hormone deficiency is. Problems tend to develop slowly, probably over a number of years.

At first, in this type of thyroid disease, the symptoms may not be so severe but are very unnoticeable. At first, it’s just weight gain and fatigue. But as the metabolism continues to slow down, you may develop some very noticeable problems.

Hypothyroidism Symptoms (in adults):

Enlarged thyroid gland (goiter) about 15 times the normal size, fatigue, dry skin, weight gain, constipation, irregular or heavier than normal menstrual periods. The patient can also experience pain, stiffness, or swelling in the joints, muscle aches, tenderness, and stiffness.

Other symptoms include hair loss, brittle nails, irregular heartbeat (slowed heart rate), depression, hoarseness, muscle weakness, puffy eyes, increased sensitivity to cold, high blood cholesterol levels impaired memory.

Hypothyroidism Symptoms (in infants):

Generally, hypothyroidism occurs most often in middle-aged and older women. However, anyone can develop the condition, even infants. Some infants are born with an underactive thyroid gland or a missing thyroid gland (congenital hypothyroidism).

The symptoms are yellowing of the skin and whites of the eyes (jaundice). Mainly, this occurs when an infant’s liver can’t metabolize a substance called bilirubin, has difficulty breathing, hoarse crying, an umbilical hernia, a large, protruding tongue.

If hypothyroidism in infants is left untreated, even mild cases can lead to severe cases. As the disease progresses, infants are likely to have trouble feeding and may fail to grow, hence developing abnormally. They may face problems like constipation, poor muscle tone, excessive sleepiness.

Hypothyroidism Symptoms (in children and teens):

Generally, children and teens with hypothyroidism have the same signs and symptoms as adults. But they also experience symptoms like poor growth, resulting in short stature, delay in the development of permanent teeth, delay in puberty, poor mental development.

Hypothyroidism should not be left untreated as it can cause peripheral neuropathy (nerve damage), heart-related diseases, infertility, and many other complications.

Symptoms of Hyperthyroidism:

The different symptoms of hyperthyroidism include enlarged thyroid gland (2-3 times), increased BMR, increased heart rate, increased pulse rate and increased cardiac output, high blood pressure, hair loss, increased body temperature.

Other than that, frequent bowel movements, reduced body weight or weight loss, and emaciation due to rapid oxidation of even stored food, osteoporosis, nervousness, tremors, and restlessness are also the symptoms of hyperthyroidism.

Peculiar symptoms of hypothyroidism are oedema behind the eyes, causing bulging eyeballs with a staring look and less blinking. It can be corrected by surgical removal of a part of the gland. Bulging eyeballs alone stand bold when the question “what is the difference between hypothyroidism and hyperthyroidism?” is raised.

what is the difference between hypothyroidism and hyperthyroidism
By Elsewhere Living Museum/ Flickr/ Copyright 2022

What is the Difference between Hypothyroidism and Hyperthyroidism?: Diseases Caused By Them

When it comes to diseases, under the topic, “what is the difference between hypothyroidism and hyperthyroidism?”, the following is a list of diseases caused by hypothyroidism and hyperthyroidism, respectively:

Diseases caused by hypothyroidism:


It is a disease of infants called cretin. It is caused due to hypothyroidism during the pregnancy, which causes defective development of the baby. It is characterized by decreased BMR (50% than normal), stunted growth, retarded mental development,  low I.Q., and delayed puberty.

Decreased body temperature, heart rate, pulse rate, blood pressure, and cardiac output, reduced urine output, dry skin, deaf-mutism, pigeon’s chest are the other symptoms of cretinism. It can be corrected by thyroxine administration.


It occurs due to a deficiency of thyroxine in adults. Like cretinism, it also has low BMR (by 30-40%), low body temperature, reduced heart rate, low cardiac output, less alertness. But the peculiar feature is that the face and hands become swollen due to the deposition of albuminous myxomatous tissue. In females, it is more common and causes irregular menstrual cycles and reproductive failure.

Endemic or Simple Goitre or Colloid Goitre:

It occurs due to the deficiency of iodine (I2) in drinking water accompanied by cretinism or myxoedema. It is characterized by enlargement of the thyroid gland due to an increase in the number and size of acinar cells of the thyroid gland. To prevent goiter, use iodized table salt.

The type of goiter is different in both types of thyroid disorders which again can answer the question: “what is the difference between hypothyroidism and hyperthyroidism?”

Hashimoto’s Thyroiditis:

This autoimmune disorder, Hashimoto’s thyroiditis, occurs due to age-factor or injury to the thyroid gland causing hyposecretion. It is also called autoimmune thyroiditis; it is an autoimmune disease. When thyroid hormone’s (thyroxine) secretion falls up to the minimal limit, antibodies destroy the thyroid gland.

Diseases caused by Hyperthyroidism:

Graves disease:

Graves disease is a common autoimmune condition/ autoimmune disease that results in the overproduction of thyroid hormones (hyperthyroidism). Although Graves disease may affect anyone, it’s more common among women and people younger than age 40. Although there are other reasons/ disorders that can lead to hyperthyroidism, graves disease is the most common of them all.

This disease is one of the main answers to “what is the difference between hypothyroidism and hyperthyroidism?” This autoimmune disease is generally the underlying cause of hyperthyroidism. Primary treatment options include reducing the amount of thyroid hormones that the body produces and lessening the severity of symptoms.

What is the Difference between Hypothyroidism and Hyperthyroidism?: Treatment

A blood test for TSH (thyroid-stimulating hormone) is done to detect thyroid hormone levels related problems. TSH stimulates thyroid hormone production. The thyroid takes commands from the pituitary gland via TSH to release thyroid hormones.

Both hyperthyroidism and hypothyroidism can be detected through a blood test. TSH is seen to be high when your body is not making enough thyroid hormone (hypothyroidism), and TSH is detected to be low when it makes too much (hyperthyroidism).

There lies a vast difference in the treatment of hypothyroidism vs. the treatment of hyperthyroidism. However, the test does not tell the cause of high or low TSH levels. If your test results are abnormal, your healthcare provider will probably ask you to get additional tests done to determine the exact cause of abnormal thyroid hormone levels.

The difference in the treatment can be another answer for the topic: “what is the difference between hypothyroidism and hyperthyroidism?”

Treating Hyperthyroidism:

The treatment of hyperthyroidism starts with treating the symptoms of hyperthyroidism. Treatment options include methimazole (Tapazole) if you have Graves disease. Beta-blockers are prescribed first, which can help to reduce heart rate and lower tremors. Other treatments are then prescribed to treat the cause of hyperthyroidism.

Healthcare providers may prescribe antithyroid medications as well. These medications block the production of thyroid hormones.

If the above treatments do not work or if hyperthyroidism is due to other various causes, the alternative options include destroying the thyroid cells with radioactive iodine or removing the gland with surgery. For some types of hyperthyroidism, surgery necessarily involves partial removal of half of the thyroid gland (known as a lobectomy) with the thyroid adenoma.

For nearly all the other types of hyperthyroidism and Graves disease, the surgery is a roughly total thyroidectomy (that is, all parts of the thyroid are removed). A total thyroidectomy is the only option left that gives an immediate cure for hyperthyroidism in such cases.

Surgical removal of the thyroid gland is not the most common method for treating hyperthyroidism; however, it can be necessary in some cases based on the specific cause of the condition and the patient’s preference.

Treating Hypothyroidism:

Hypothyroidism can be treated with the help of supplemental thyroid hormone. The synthetic version of thyroid hormone is called L-thyroxine or levothyroxine, which can help to bring back normal thyroid levels. The doctor will prescribe a dose according to the need, keeping in mind the weight and age.

what is the difference between hypothyroidism and hyperthyroidism
By Andy Melton/ Flickr/ Copyright 2022
what is the difference between hypothyroidism and hyperthyroidism
By Doctor 4U/ Flickr/ (www.doctor-4-u.co.uk)

Basically, the goal is to get your TSH levels back in the normal range and improve the symptoms; hence, monitoring of TSH levels periodically is done by the doctor to see if adjustments in the dosage are required.

Suppose you realize that you are facing any of the above symptoms related to any of the aforementioned diseases. In that case, it’s best to seek professional medical advice and get yourself medically reviewed as soon as possible. That’s all the information you need to learn on the topic “what is the difference between hypothyroidism and hyperthyroidism?” 

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