Hypothyroidism vs Hyperthyroidism

Difference between thyroid and hyperthyroidism

Hypothyroidism vs. Hyperthyroidism: What’s the Difference?

y Elizabeth Shimer Bowers | Medically reviewed by Niya Jones, MD, MPH


The butterfly-shaped thyroid gland in the front of your neck acts as the control center for your body. Hormones secreted by the thyroid help maintain the brain, heart, muscles, and other organs, and help the body to use energy properly. So when something goes awry that leads to underactive thyroid or overactive thyroid, your metabolism either revs up too high or slows way down. These two conditions — hyperthyroidism and hypothyroidism — affect the thyroid in different ways and therefore have distinct symptoms.


“The major difference between hypothyroidism and hyperthyroidism is the thyroid’s hormone output,” says Minisha A. Sood, MD, anendocrinologist at Lenox Hill Hospital in New


In simple terms, with hypothyroidism, or underactive thyroid, the thyroid gland doesn’t make enough thyroid hormone for the body’s needs. With hyperthyroidism, or overactive thyroid, the thyroid makes too much, explains Dr. Sood.


The most common cause of hypothyroidism is an autoimmune disease called Hashimoto’s disease, a condition where the immune system makes antibodies that destroy thyroid cells and stop them from making the thyroid hormone.


The most common form of hyperthyroidism is a condition called Grave’s disease. Some people with Grave’s disease have swelling in the front of their neck from an enlarged thyroid gland, called a goiter, as well as eyes that appear enlarged due to inflammation.


Symptoms of Hypothyroidism Versus Hyperthyroidism


Think of hypothyroidism as a clock winding down. “Your whole metabolism slows down — the heart rate is slower than normal, the intestinal tract becomes sluggish, and there is less heat production,” says Mario Skugor, MD, an endocrinologist who specializes in thyroid disorders at the Cleveland Clinic.


As a result of an underactive thyroid you may experience:


Fatigue Forgetfulness Dry skin Dry hair Brittle nails Constipation Weight gain Muscle cramps Depression Decreased menstrual flow Swelling in the front of the neck (goiter)


“The weight gain that often accompanies hypothyroidism is a funny thing,” Dr. Skugor notes. “If a person with underactive thyroid can force him- or herself to maintain a normal activity level, he or she may only gain a few pounds,” he says. “But some people with hypothyroidism feel so tired they stop exercising, sleep more, and change their routine, which causes more weight gain.”


Think of hyperthyroidism, on the other hand, as a racing car engine. With an overactive thyroid, all body functions tend to speed up. “People with hyperthyroidism will have symptoms.


As a result of an overactive thyroid you may experience:


Feeling hot SweatingProblems falling asleep Racing thoughts Difficulty focusing on one task Forgetfulness Change in bowel habits, where bowels are looser Elevated heart rate and palpitations Anxiety, nervousness, or irritability Weight loss Menstrual problems Fatigue


“It’s important to note that weight loss associated with overactive thyroid is not happy weight loss,” Skugor explains. “It is associated with muscle weakness and constant fatigue, so it isn’t something you want.”


If you experience any of the above symptoms of thyroid disorders — either underactive thyroid or overactive thyroid — see your health care professional. He or she can order tests to see if your thyroid hormone levels are in the normal range, and if they are not, can provide treatments to ease your symptoms.