Endocrine dysfunction
The effects of hypothyroidism and hyperthyroidism on the body
Lucy Talbot
ATAR Human Biology Unit 3
February 15, 2022
, ATAR Human Biology Unit 3
Introduction
The endocrine system is a network of glands and organs that produce hormones. Hormones are the
body’s internal chemical messengers, integrating the activities of widely separated organs. Unlike the
nervous system, the endocrine system’s effects are slow to appear, longer lasting, and usually occur at
distant target sites. Hormones carry the information that controls the rate at which glands and other
organs work. When a gland is working harder than the body needs it to, the hormone control system
switches it off; and when the body needs the gland to speed up, the system turns on the switch again.
Endocrine disorders occur when the body is unable to control these switches, which results in a wide
range of symptoms that influence growth, development, metabolism, sexual function, and mood.
A major organ of the endocrine system is the thyroid, a gland that controls metabolism, including the
maintenance of body weight, rate of energy use, and heart rate. Thyroid stimulating hormone releasing
factors (TSHrf) are released from the hypothalamus and stimulate the release of TSH from the anterior
pituitary, which in turn stimulates release of thyroid hormones by the thyroid gland in the neck. When
the thyroid is working correctly, it is constantly producing and releasing hormones that regulate the
metabolic rate and in turn affect the way energy is used in the body. But when the thyroid produces
either too much or too little hormone, a range of different disorders may arise. The two major endocrine
dysfunctions of the thyroid gland are hypothyroidism and hyperthyroidism.
Hypothyroidism
Hypothyroidism or underactive thyroid is a disorder of the endocrine system in which the thyroid gland
doesn’t produce enough of its major hormones, triiodothyronine (T3) and thyroxine (T4), mostly due to
decreased iodine levels in the body.
Causes
Hypothyroidism is most commonly caused by Hashimoto’s thyroiditis, an autoimmune disorder that
leads to a chronic inflammation of the thyroid which results in the hyposecretion of thyroid hormones.
The immune system creates antibodies that attack thyroid cells as if they were dangerous and wrongly
sends out disease-fighting agents that damage cells and lead to cell death. Hypothyroidism may also be
caused by thyroiditis, an inflammation of the thyroid in which stored hormones leak from the gland.
Blood hormone levels rise and induce thyrotoxicosis, which, after a few months, slowly drops to cause
hypothyroidism. Lastly, congenital hypothyroidism may occur in babies born with an underdeveloped
thyroid.
Signs and symptoms
Objective warning signs of hypothyroidism include weight gain, high blood cholesterol, low body
temperature, anaemia, or heart failure. Subjective symptoms of hypothyroidism include puffiness in the
face, fatigue, numbness, confusion, or depression.
Treatment
Hypothyroidism is most commonly treated with oral medications in order to replace the hormones that
the thyroid is unable to produce. Levothyroxine lowers blood cholesterol levels and slows or reverses
weight gain altogether. It is essential however that the ingestion of medication is carefully monitored to
ensure hypothyroidism is treated but hyperthyroidism is not induced.
Impact
Individuals who have hypothyroidism and are taking medication generally have no major issues and can
lead a healthy life. However, quality of life may be decreased if left untreated, leading to health problems
such as obesity, joint pain, infertility, and heart disease. In women who are pregnant, untreated
hypothyroidism can be particularly dangerous, as iodine is essential for proper development of the
foetus. Lack of iodine can result in severe mental and physical disabilities.
The effects of hypothyroidism and hyperthyroidism on the body
Lucy Talbot
ATAR Human Biology Unit 3
February 15, 2022
, ATAR Human Biology Unit 3
Introduction
The endocrine system is a network of glands and organs that produce hormones. Hormones are the
body’s internal chemical messengers, integrating the activities of widely separated organs. Unlike the
nervous system, the endocrine system’s effects are slow to appear, longer lasting, and usually occur at
distant target sites. Hormones carry the information that controls the rate at which glands and other
organs work. When a gland is working harder than the body needs it to, the hormone control system
switches it off; and when the body needs the gland to speed up, the system turns on the switch again.
Endocrine disorders occur when the body is unable to control these switches, which results in a wide
range of symptoms that influence growth, development, metabolism, sexual function, and mood.
A major organ of the endocrine system is the thyroid, a gland that controls metabolism, including the
maintenance of body weight, rate of energy use, and heart rate. Thyroid stimulating hormone releasing
factors (TSHrf) are released from the hypothalamus and stimulate the release of TSH from the anterior
pituitary, which in turn stimulates release of thyroid hormones by the thyroid gland in the neck. When
the thyroid is working correctly, it is constantly producing and releasing hormones that regulate the
metabolic rate and in turn affect the way energy is used in the body. But when the thyroid produces
either too much or too little hormone, a range of different disorders may arise. The two major endocrine
dysfunctions of the thyroid gland are hypothyroidism and hyperthyroidism.
Hypothyroidism
Hypothyroidism or underactive thyroid is a disorder of the endocrine system in which the thyroid gland
doesn’t produce enough of its major hormones, triiodothyronine (T3) and thyroxine (T4), mostly due to
decreased iodine levels in the body.
Causes
Hypothyroidism is most commonly caused by Hashimoto’s thyroiditis, an autoimmune disorder that
leads to a chronic inflammation of the thyroid which results in the hyposecretion of thyroid hormones.
The immune system creates antibodies that attack thyroid cells as if they were dangerous and wrongly
sends out disease-fighting agents that damage cells and lead to cell death. Hypothyroidism may also be
caused by thyroiditis, an inflammation of the thyroid in which stored hormones leak from the gland.
Blood hormone levels rise and induce thyrotoxicosis, which, after a few months, slowly drops to cause
hypothyroidism. Lastly, congenital hypothyroidism may occur in babies born with an underdeveloped
thyroid.
Signs and symptoms
Objective warning signs of hypothyroidism include weight gain, high blood cholesterol, low body
temperature, anaemia, or heart failure. Subjective symptoms of hypothyroidism include puffiness in the
face, fatigue, numbness, confusion, or depression.
Treatment
Hypothyroidism is most commonly treated with oral medications in order to replace the hormones that
the thyroid is unable to produce. Levothyroxine lowers blood cholesterol levels and slows or reverses
weight gain altogether. It is essential however that the ingestion of medication is carefully monitored to
ensure hypothyroidism is treated but hyperthyroidism is not induced.
Impact
Individuals who have hypothyroidism and are taking medication generally have no major issues and can
lead a healthy life. However, quality of life may be decreased if left untreated, leading to health problems
such as obesity, joint pain, infertility, and heart disease. In women who are pregnant, untreated
hypothyroidism can be particularly dangerous, as iodine is essential for proper development of the
foetus. Lack of iodine can result in severe mental and physical disabilities.
