Endocrine System

Chapter 8

ENDOCRINE SYSTEM

Introduction to Endocrine System 

The endocrine system is a network of glands that produce and release hormones that help to control many important body functions, especially the body’s ability to change calories into energy that powers cells and organs.

Functions 

• The main function of endocrine glands is to secrete hormones directly into the bloodstream. Hormones are chemical substances that affect the activity of another part of the body (target site). In essence, hormones serve as messengers, controlling and coordinating activities throughout the body. 

• Upon reaching a target site, a hormone binds to a receptor, much like a key fits into a lock. Once the hormone locks into its receptor, it transmits a message that causes the target site to take a specific action. Hormone receptors may be within the nucleus or on the surface of the cell.

• Ultimately, hormones control the function of entire organs, affecting such diverse processes as growth and development, reproduction, response to stimuli (stress and injury) and sexual characteristics. Hormones also influence the way the body uses and stores energy and control the volume of fluid and the levels of salts and sugar (glucose) in the blood. Very small amounts of hormones can trigger very large responses in the body.

• Although hormones circulate throughout the body, each type of hormone influences only certain organs and tissues. Some hormones affect only one or two organs, whereas others have influence throughout the body. For example, thyroidstimulating hormone, produced in the pituitary gland, affects only the thyroid gland. In contrast, thyroid hormone, produced in the thyroid gland, affects cells throughout the body and is involved in such important functions as regulating growth of cells, controlling the heart rate, and affecting the speed at which calories are burned.

• Most hormones are proteins. Others are steroids, which are fatty substances derived from cholesterol.  

Glands of the Endocrine System 

Each gland of the endocrine system releases specific hormones into bloodstream. These hormones travel through blood to other cells and help control or co-ordinate many body processes. Endocrine glands include:

• Pituitary gland: A gland found at the base of brain behind the sinuses. It is often called the “master gland” because it influences many other glands, especially the thyroid. The pituitary gland produces several hormones. The front part of pituitary gland commonly called the anterior pituitary produces the following types of hormones.

• Growth hormone: Growth hormone promotes the growth in childhood. For adults, it helps to maintain healthy muscle and bone mass.

• Prolactin: In women, it stimulates milk production. In males, low levels are linked to sexual problems; however, in most of the males, these hormones are inactive.

• Adrenocorticotropic hormone: This hormone promotes the production of cortisol, which helps to reduce stress, and maintains healthy blood pressure.

• Thyroid-stimulating hormone: This hormone helps to regulate the body’s thyroid, which is crucial in maintaining a healthy metabolism.

• Luteinizing hormone: In women, this hormone regulates estrogen. In men, it regulates testosterone.

• Follicle-stimulating hormone: Found in both men and women. It stimulates the releasing of eggs in women and in man, it helps ensure the normal function of sperm production.The back part of the pituitary gland is called the posterior pituitary. It produces the following two hormones.

• Oxytocin: Oxytocin is involved in a variety of processes, such as contracting the uterus during childbirth and also promotes milk flow in nursing mothers.

• Antidiuretic hormone: Commonly referred to as vasopressin, this hormone helps to regulate water balance in the body. 

Hypothalamus 

A part of brain that controls hormone production by releasing different chemicals to the pituitary gland. The hypothalamus is in control of pituitary hormones by releasing the following types of hormones:

1. Thyrotrophic-releasing hormone 
2. Growth hormone-releasing hormone 
3. Corticotrophin-releasing hormone 
4. Gonadotropin-releasing hormone  

Adrenal glands: Two adrenal glands located on the top of the kidneys' release the hormone cortisol and adrenaline. Adrenal glands are involved in:

1. Promoting proper cardiovascular function
2. Properly utilizing carbohydrates and fats
3. Helps to distribute stored fat
4. Promotes healthy gastrointestina

• Thyroid: A butterfly-shaped gland in the front of the neck that controls metabolism. 

• Ovaries: The ovaries are two small organs located on either side of the uterus in a woman’s body that release eggs and produce sex hormones. This gland produces both estrogen and progesterone, which promote the development of breasts. They also help to maintain healthy menstrual periods.

• Islet cells in the pancreas: Cells in the pancreas control the release of the hormone's insulin and glucagon. The main function of the pancreas is to maintain healthy blood sugar levels.

• Parathyroid: This gland is vital to proper bone development because it helps in controlling both calcium and phosphorous levels in the body. The parathyroid gland is actually a group of four small glands located behind the thyroid gland.

• Pineal gland: A gland found near the center of the brain that may be linked to sleep patterns.

• Testes: The male reproductive glands that produce sperm and sex hormone testosterone. It regulates production of sperm and stimulates the development and maintenance of male secondary sex characteristics, such as beard growth and deepening of the voice. 

• Thymus: This gland secretes hormones that are commonly referred to as humoral factors and are important during puberty. The role of these hormones is to make sure a person develops a healthy immune system.

Causes of Endocrine Disorders 

Endocrine disorders are typically grouped into two categories:

1. Endocrine disease that results when a gland produces too much or too little of an endocrine hormone, called a hormone imbalance.
2. Endocrine disease due to the development of lesions (such as nodules or tumors) in the endocrine system, which may or may not affect hormone levels

• The endocrine’s feedback system helps control the balance of hormones in the bloodstream. If body has too much or too little of a certain hormone, the feedback system signals the proper gland or glands to correct the problem. A hormone imbalance may occur if this feedback system has trouble keeping the right level of hormones in the blood stream, or if body does not clear them out of the blood stream properly

Types of Endocrine Disorders  

Numerous problems can occur in the endocrine system. These can be considered as excessive or deficient hormone production. Endocrine organs are also prone to tumours (adenomas) which can overproduce hormones. Some problems of the endocrine system include:

• Diabetes mellitus: Too much sugar in the blood caused by problems with insulin production. This includes type 1 diabetes (deficiency of insulin) and type 2 diabetes (initially excessive, then deficiency of insulin). 

• Diabetes insipidus: The most common abnormality with the dysfunction of posterior pituitary is diabetes insipidus. This disorder is due to defects in antidiuretic hormone receptors or an inability to secrete ADH. 

• Hyperthyroidism: The thyroid gland produces too much thyroid hormone, leading to weight loss, fast heart rate, sweating, and nervousness. The most common cause for an overactive thyroid is an autoimmune disorder called Grave’s disease. 

•  Hypothyroidism: The thyroid gland does not produce enough thyroid hormone, leading to fatigue, constipation, dry skin, and depression. The underactive gland can cause slowed development in children. Some types of hypothyroidism are present at birth.

• Menstruation abnormalities: Polycystic ovarian syndrome (PCOS), pituitary adenoma or primary ovarian failure (POF) may cause irregular menstruation or lack of menstruation.

• Parathyroid problems: An enlargement of one or more of the parathyroid glands can lead to high calcium levels in the blood (hypercalcemia).

• Pituitary adenomas: These are tumours of the pituitary gland that can make too much of a certain hormone or cause deficiencies of hormones. These tumours can be small (microadenomas) or large (macroadenomas). 

Diabetes Mellitus 

• Diabetes mellitus is a metabolic disorder, in which glucose level in the blood is much higher than normal (hyperglycemia) and hence this condition is also commonly referred to as sugar disease. The defect in this condition is that, either the pancreas does not produce enough insulin or it produces sufficient insulin, but the cells of the body are unable to use the insulin properly. Insulin, a hormone released from the pancreas, controls the amount of glucose in the blood. Glucose in the bloodstream stimulates the pancreas to produce insulin. Insulin allows glucose to move from the blood into the cells. Once inside the cells, glucose is converted to energy, which is used immediately, or the glucose is stored as fat or glycogen until it is needed. The levels of glucose in the blood vary normally throughout the day. They rise after a meal and return to normal within about 2 hours after eating. Once the levels of glucose in the blood return to normal, insulin production decreases. The variation in blood glucose levels is usually within a narrow range, about 70 to 110 milligrams per deciliter (mg/dL) of blood in healthy people. If people eat a large amount of carbohydrates, the levels may increase more. People older than 65 years tend to have slightly higher levels, especially after eating.

Multitude of Mechanisms 

• The body’s response to blood sugar requires the co-ordination of an array of mechanisms. Failure of any one component involved in insulin regulation, secretion, uptake or breakdown can lead to the buildup of glucose in the blood.

• β-cells damage: Destruction or damage to the β-cells, lead to increased levels of blood glucose. 

Classification 

There are two major types of diabetes: Primary and Secondary.
Primary or Idiopathic Diabetes Mellitus
It is most common with unknown cause of diabetes. It is further divides into

• Type 1 Diabetes (5-10%) 
• Type 2 Diabetes (90-95%) 
• Gestational Diabetes. 

Type I Diabetes mellitus (Insulin dependent diabetes mellitus (IDDM) or Juvenile diabetes):

• It results from the body’s failure of insulin production by β-cells of the islets of Langerhans in the pancreas, leading to insulin deficiency. This type can be further classified as immune mediated or idiopathic. Most of type 1 diabetes is of the immune mediated nature, in which a T-cell mediated autoimmune attack leads to the loss of β-cells and thus insulin. Only about 10% of all people with diabetes have type 1 disease. Onset most often occurs in childhood, but most people who have type 1 diabetes develop the disease before age 30, although it can develop later in life. 

Type II Diabetes mellitus (non– insulin-dependent diabetes mellitus, or Adult/maturity onset diabetes mellitus):

• This form of diabetes, which accounts for 90% of those with diabetes, encompasses individuals who have insulin resistance, diminished tissue sensitivity to insulin, impaired β-cell function (delayed or inadequate insulin release) and excessive or inappropriate glucagon secretion. Type II diabetes may occur at any age but more common in people older than the age of 40. 

• Obesity is the chief risk factor for developing type II diabetes, and 80 to 90% of people with this disorder are overweight or obese. Because obesity causes some degree of insulin resistance, obese people need very large amounts of insulin to maintain normal blood glucose levels.

• Certain disorders and drugs can affect the way the body uses insulin and can lead to type II diabetes. High levels of corticosteroids (due to Cushing disease or taking corticosteroid drugs) and pregnancy are the most common causes of altered insulin use.

Gestational diabetes:

• Diabetes can occur temporarily during pregnancy, and it occurs in 2% to 10% of all pregnancies. Significant hormonal changes during pregnancy can lead to blood sugar elevation in genetically predisposed individuals. Blood sugar elevation during pregnancy is called gestational diabetes. 

• Gestational diabetes usually resolves once the baby is born. However, 35% to 60% of women with gestational diabetes will eventually develop type II diabetes over the next 10 to 20 years, especially in those who require insulin during pregnancy and those who remain overweight after their delivery. 

Secondary Diabetes 

• It is the type of diabetes mellitus and have definite cause of hyperglycemia. Secondary diabetes refers to elevated blood sugar levels from another medical condition. Secondary diabetes may develop when the pancreatic tissue responsible for the production of insulin is destroyed by disease, such as chronic pancreatitis (inflammation of the pancreas by toxins like excessive alcohol), trauma, or surgical removal of the pancreas.

• Diabetes can also result from other hormonal disturbances, such as excessive growth hormone production (acromegaly) and Cushing’s syndrome. In acromegaly, a pituitary gland tumor at the base of the brain causes excessive production of growth hormone, leading to hyperglycemia. In Cushing’s syndrome, the adrenal glands produce an excess of cortisol, which promotes blood sugar elevation

Pathophysiology 

• Insulin is the principal hormone that regulates the uptake of glucose from the blood into most cells of the body, especially liver, muscle and adipose tissue. Therefore, deficiency of insulin or the insensitivity of its receptor plays a central role in all forms of diabetes mellitus.

• The body obtains glucose from three main places: the intestinal absorption of food, the breakdown of glycogen; the storage form of glucose found in the liver, and gluconeogenesis, the generation of glucose from non-carbohydrate substrates in the body.

• Insulin plays a critical role in balancing glucose levels in the body. Insulin can inhibit the breakdown of glycogen or the process of gluconeogenesis, it can stimulate the transport of glucose into fat and muscle cells, and it can stimulate the storage of glucose in the form of glycogen. 

• Insulin is released into the blood by βcells, found in the islets of Langerhans in the pancreas, in response to rising levels of blood glucose, typically after eating. Insulin is used by about two-thirds of the body’s cells to absorb glucose from the blood for use as fuel, for conversion to other needed molecules, or for storage. Lower glucose levels result in decreased insulin release from the β-cells and in the breakdown of glycogen to glucose. This process is mainly controlled by the hormone glucagon, which acts in the opposite manner to insulin.  

Clinical Manifestations of Diabetes Mellitus 

• People with type II diabetes often do not have any symptoms. When symptoms do occur, they are often ignored because they may not seem serious. Symptoms in type I diabetes usually occurs much more suddenly and are often severe.

• The early symptoms of untreated diabetes are related to elevated blood sugar levels, and loss of glucose in the urine (glycosuria). 

• In response to glycosuria, kidneys excrete additional water to dilute the excessive glucose, called polyuria.

• High amount of glucose in the urine can cause increased urine output and lead to dehydration. Dehydration causes increased thirst (polydipsia) and water consumption.

• The inability of insulin to perform normally has effects on protein, fat and carbohydrate metabolism. Insulin is an anabolic hormone, that is, one that encourages storage of fat and protein. 

• Excessive loss of calories in urine results in weakness. The loss of energy in turn, causes excessive hunger called polyphagia.

• A relative or absolute insulin deficiency eventually leads to weight loss despite an increase in appetite.

• Patients with diabetes are prone to developing infections of the bladder, skin, and vaginal areas. 

• Fluctuations in blood glucose levels can lead to blurred vision. Extremely elevated glucose levels can lead to lethargy and coma.

• Itching skin, especially in the groin or vaginal area. 

Effects of Diabetes 

• Poor Control of Diabetes can lead to an Increased Risk of Following Diseases:

• Ketoacidosis: The cellular metabolism of untreated type I diabetes is similar to that of a starving person. Because insulin is not present to aid the entry of glucose into body cells, most cells use fatty acids to produce ATP. Stores of triglycerides in adipose tissue are catabolized to yield fatty acids and glycerol. The by-product of fatty acid breakdown is organic acid called ketones and ketone bodies. Accumulation and buildup of ketones causes blood pH to fall, a condition is known as Ketoacidosis, unless treated quickly, ketoacidosis can cause death.

• Cardiovascular disease: The breakdown of stored triglycerides also causes weight loss. As lipids are transported by the blood from storage depots to cells, lipid particles are deposited on the walls of blood vessels, leading to atherosclerosis and multitude of cardiovascular problems, including.

• Blindness: A major complication of diabetes is loss of vision either due to cataracts (excessive glucose attaches to lens proteins, causing cloudiness) or due to damage to blood vessels of the retina. 

• Kidney and bladder failure: Severe kidney problems also may result from damage to renal blood vessels. 

• Other complication include: Gum disease, foot and leg infections, sexual dysfunction and complications of pregnancy.  

Diagnosis 

Elevated blood glucose level is often the fundamental basis for the diagnosis of diabetes mellitus. Regular checking of fasting and post meal blood glucose level is a standard method of diagnosis. A random plasma glucose concentration above 250mg/dL is also an indication of diabetes mellitus.

• Blood sugar estimation using a glucometer can be done at different times and the three common time points are:

• Fasting Plasma Glucose (FPG): Testing blood sugar levels after 8 hours of fasting, usually overnight fasting.

• Postprandial Plasma Glucose (PPG): Testing blood sugar levels 2 hours after a meal (usually it is breakfast). 

• Random or casual sugar: Any time of the day irrespective of meal intake. 

• Oral Glucose Tolerance Test (OGTT): Test done to confirm the diagnosis in doubtful cases (i.e., cases were FPG and/or PPG are in the borderline range). In this test, one has to drink 75 g glucose (sugar) in water on empty stomach and blood sugar is to be tested after 2 hour. 

Management and Treatment

• The major goal in treating diabetes is to keep blood sugar (glucose) levels as close to normal as possible, without causing abnormally low levels of blood sugar (hypoglycemia). 

• Lifestyle modifications are the cornerstone of management of diabetes mellitus and include the healthy diet (high protein and low carbohydrate and fat diet), management of stress, avoidance of alcohol and tobacco etc. are found to be effective to control the diabetes along with drugs. 

• Type I diabetes is treated with insulin, exercise, and a diabetic diet. Type II diabetes is treated first with weight reduction, a diabetic diet, and exercise.

• Patients with type I diabetes mellitus require lifelong insulin therapy. Most require 2 or more injections of insulin daily, with doses adjusted on the basis of selfmonitoring of blood glucose levels.

• Early initiation of pharmacologic therapy is associated with improved glycemic control and reduced long-term complications in type II diabetes. Drug classes used for the treatment of type II diabetes include the following.
• Insulin therapy: Some people who have type II diabetes need insulin therapy as well. In the past, insulin therapy was used as last resort, but today it is often prescribed sooner because of its benefits. Regular monitoring of the blood and urine glucose level, during treatment is essential part of management. These results indicate the appropriate change required in the treatment.

• The overdose of insulin or hypoglycemic agent may result in hypoglycemia. Symptoms of hypoglycemia include. Anxiety, confusion, extreme hunger, fatigue, irritability, sweating or clammy skin and trembling hands which need immediate treatment. If sugar levels continue to fall during an insulin overdose, serious complications such as Seizures, unconsciousness and pale skin can occur. Untreated hypoglycemia may cause permanent brain damage and hypoglycemic coma.

Thyroid Diseases

• Thyroid is a small butterfly-shaped gland inside the neck, located in front of the trachea (windpipe) and below the larynx (voicebox). It produces two thyroid hormones, triiodothyronine (T3) and thyroxine (T4) that travel through the blood to all tissues of the body. Thyroid hormones regulate how the body breaks down food and either uses that energy immediately or stores it for the future. In other words, thyroid hormones regulate body's metabolism as well as the consumption of oxygen and the production of heat. Pituitary glands controls how well the thyroid works by producing thyroid-stimulating hormone (TSH). The bloodstream carries TSH to the thyroid gland to produce more thyroid hormones, as needed. 

Hypothyroidism 

• Too little thyroid hormone from an underactive thyroid gland is called hypothyroidism. In hypothyroidism, the body's metabolism is slowed. Several causes for this condition exist, most of which affect the thyroid gland directly, impairing its ability to make enough hormone.

•  More rarely, there may be a pituitary gland tumor, which blocks the pituitary from producing TSH. Whether the problem is caused by the thyroid or by the pituitary gland, the result is that the thyroid is producing too few hormones, causing many physical and mental processes to become sluggish. The body consumes less oxygen and produces less body heat. 

Symptoms of Hypothyroidism: Symptoms of hypothyroidism can include,

1. Poor concentration or feeling mentally "foggy" 
2. Dry skin
3. Constipation
4. Feeling cold
5. Fluid retention
6. Muscle and joint aches 
7. Depression
8. Prolonged or excessive menstrual bleeding in women

Hyperthyroidism 

• Too much thyroid hormone from an overactive thyroid gland is called hyperthyroidism. This hormone imbalance occurs in about 1 % of all women, who get hyperthyroidism more often than men. One of the most common forms of hyperthyroidism is known as Graves' disease. This autoimmune disorder tends to run in families. The thyroid gland is producing too much hormone in hyperthyroidism, the body develops an increased metabolic state, with many body systems developing abnormal function.

• In mild cases, there may not be apparent symptoms. Symptoms and signs of hyperthyroidism can include: 

1. Tremor
2. Nervousness
3. Fast heart rate
4. Fatigue
5. Intolerance for heat
6. Increase in bowel movements 
7. Increased sweating 
8. Concentration problems 
9. Unintentional weight loss 

Thyroiditis 

Thyroiditis is inflammation of the thyroid. It occurs when the body's immune system makes antibodies that attack the thyroid. Causes of thyroiditis include:

• Autoimmune diseases like type I diabetes and rheumatoid arthritis
• Genetics
• Viral or bacterial infection 
• Certain types of medicines

Postpartus thyroiditis: It is inflammation of the thyroid after giving birth, affects 10% of women. It often goes undiagnosed because symptoms are much like the "baby blues" that may follow delivery. Women with postpartum thyroiditis may feel very tired and moody.

Hashimoto’s disease: Hashimoto’s disease is also known as chronic lymphocytic thyroiditis. It can occur at any age, but most common in middle-aged women. The disease occurs when the body’s immune system mistakenly attacks and slowly destroys the thyroid gland and its ability to produce hormones.

Hashimoto’s diagnosis and treatment: Testing the level of TSH is often the first step when screening for any type of thyroid disorder. It includes blood test to check for increased levels of TSH as well as low levels of thyroid hormone (T3 or T4) if experiencing some of the above symptoms. 

Treatment 

• There is no known cure for Hashimoto’s disease. Hormone-replacing medication is often used to raise thyroid hormone levels or lower TSH levels. It can also help relieve the symptoms of the disease. Surgery might be necessary to remove part or all of the thyroid gland in rare advanced cases of Hashimoto’s. The disease is usually detected at an early stage and remains stable for years because it progresses slowly. 

Graves’ Disease 

Graves’ is an autoimmune disorder that occurs when the body’s immune system mistakenly attacks the thyroid gland. This can cause the gland to overproduce the hormone, responsible for regulating metabolism.

The disease is hereditary and may develop at any age in men or women, but it is much more common in women ages 20 to 30. Other risk factors include stress, pregnancy and smoking.

When there is a high level of thyroid hormone in bloodstream, body’s systems speed up and cause symptoms that are common to hyperthyroidism. These include: 

• Anxiety
• Irritability
• Fatigue
• Hand tremors
• Increased or irregular heartbeat
• Excessive sweating
• Difficulty sleeping
• Diarrhoea or frequest bowel movements
• Altered menstrual cycle
• Goiter 
• Bulging eyes and vision problems.

Graves’ Disease: Diagnosis and Treatment: A simple physical exam can reveal an enlarged thyroid, enlarged bulging eyes, and signs of increased metabolism, including rapid pulse and high blood pressure. Blood tests to check for high levels of T4 and low levels of TSH, both of which are signs of Graves’ disease. A radioactive iodine uptake test may also be administered to measure how quickly thyroid takes up iodine. A high uptake of iodine is consistent with Graves’ disease.

Treatment 

There is no treatment to stop the immune system from attacking the thyroid gland and causing it to overproduce hormones. However, the symptoms of Graves’ disease can be controlled in several ways, often with a combination of treatments:

• β-blockers to control rapid heart rate, anxiety and sweating. 
• Antithyroid medications to prevent thyroid from producing excessive amounts of hormone. • Radioactive iodine to destroy all or part of thyroid. 
• Surgery to remove thyroid gland, a permanent option if one cannot tolerate antithyroid drugs or radioactive iodine. 

Successful hyperthyroidism treatment usually results in hypothyroidism and may require hormone-replacement medication from that point forward. Graves’ disease can lead to heart problems and brittle bones, if it is left untreated.

Thyroid Nodules 

• Nodules are lumps or abnormal masses within the thyroid. Nodules can be caused by benign cysts, benign tumors, or, less commonly, by cancers of the thyroid (most nodules are not cancerous). Nodules may be single or multiple and can vary in size. If nodules are excessively large, they may causes symptoms related to compression of nearby structures.

• Some thyroid nodules may produce too much thyroid hormone and cause hyperthyroidism, or become too large, interfering with breathing or swallowing or causing neck discomfort.

Thyroid Cancer  

• Thyroid cancer occurs in the cells of the thyroid gland, and it is more common among adult women than men or youth. About 2/3rd of cases occurs in people under age 55. There are different kinds of thyroid cancer, depending upon the specific cell type within the thyroid that has become cancerous. Most cases of thyroid cancer have a good prognosis and high survival rates, especially when diagnosed in its early stages.  

Causes

• Thyroid cancer occurs when cells in thyroid undergo genetic changes (mutations). The mutations allow the cells to grow uncontrollably, multiply rapidly and produce lump. The cells also lose the ability to die, as normal cells would. The accumulating abnormal thyroid cells form a tumor. The abnormal cells can invade nearby tissue and can spread throughout the body.

• Exact cause of thyroid cancer is not clear but there are a number of things that can increase risk of thyroid cancer includes:
• Other thyroid conditions, such as an inflamed thyroid (thyroiditis) or goitre – but not an overactive thyroid or underactive thyroid

1.  A family history of thyroid cancer. 
2.  Radiation exposure in childhood (Radiotherapy). 
3.  Obesity. 
4.  A bowel condition called familial adenomatous polyposis (FAP). 
5.   Acromegaly, a rare condition where the body produces too much growth hormone.

Symptoms 

Thyroid cancer typically does not cause any signs or symptoms early in the disease. As thyroid cancer grows, it may cause:

• A lump that can be felt through the skin on neck 
• Changes to voice, including increasing hoarseness
• Difficulty in swallowing 
• Pain in neck and throat. 
• Swollen lymph nodes in neck

Types of Thyroid Cancer

• Papillary thyroid cancer: The most common form of thyroid cancer, papillary thyroid cancer arises from follicular cells, which produce and store thyroid hormones. Papillary thyroid cancer can occur at any age, but most often it affects people in age 30 to 50.  

• Follicular thyroid cancer (Hurtled cell thyroid cancer): Follicular thyroid cancer also arises from the follicular cells of the thyroid. It usually affects people older than age 50. Hürthle cell cancer of the thyroid gland is a rare and potentially more aggressive type of follicular thyroid cancer which accounts for only about 3-10% of all differentiated thyroid cancers. 

• Medullary thyroid cancer: Medullary thyroid cancer begins in thyroid cells called C cells, which produce the hormone calcitonin. Elevated levels of calcitonin in the blood can indicate medullary thyroid cancer at a very early stage. Certain genetic syndromes increase the risk of medullary thyroid cancer, although this genetic link is uncommon.
• Anaplastic thyroid cancer: Anaplastic thyroid cancer is a rare and rapidly growing cancer that is very difficult to treat. Anaplastic thyroid cancer typically occurs in adults (age 60 and older). 

• Thyroid lymphoma: Thyroid lymphoma is a rare form of thyroid cancer that begins in the immune system cells in the thyroid and grows very quickly. Thyroid lymphoma typically occurs in older adults.
• Radioactive iodine treatment: Radioactive iodine (I-131), an isotope of iodine emits radiation. When a small dose of I-131 is swallowed, it is absorbed into the bloodstream in the gastrointestinal (GI) tract and concentrated from the blood by the thyroid gland, where it begins destroying the gland's cells. 

Goiter 

A goiter simply describes enlargement of the thyroid gland, regardless of cause. It may be associated with hypothyroidism, hyperthyroidism, or normal thyroid function.

Types of Goiters 

Goiters have many causes. As a result, there are different types. These include:

 Colloid Goiter (Endemic): A colloid goiter develops from the lack of iodine, a mineral essential to the production of thyroid hormones. People who get this type of goiter usually live in areas where iodine is scarce.

Non-toxic (Sporadic): The cause of a non-toxic goiter is usually unknown, though it may be caused by medications like lithium. Lithium is used to treat mood disorders such as a bipolar disorder. Non-toxic goiters do not affect the production of thyroid hormone, and thyroid function is healthy. They are also benign.

Toxic Nodular or Multinodular Goiter: This type of goiter forms one or more small nodules as it enlarges. The nodules produce their own thyroid hormone, causing hyperthyroidism. It generally forms as an extension of a simple goiter.

 Causes 

Iodine deficiency is the main cause of goiters. Iodine is essential to help thyroid to produce thyroid hormones. When person do not have enough iodine, the thyroid works extra hard to make thyroid hormone, causing the gland to grow larger.

 Symptoms 

• Swelling
• Coughing
• Throat tightness
• Trouble breathing
• Coughing
• Fast heart rate
• Heat intolerance
• Shortness of breath
• Throat tightness
• Underactive thyroid
• Weight gain.

Treatments 

Observation: Monitoring for changes or improvement.

Radioactive iodine therapy: A radioactive medicine taken by mouth to reduce the functioning of the thyroid gland or completely destroy it.

Antithyroid agent: Prevents the thyroid gland from making or releasing thyroid hormone.

Hormone: Affects body processes by regulating the activity of the organs. 

Disorders of Sex Hormones 

• The sex hormones are a group of hormones responsible for controlling puberty, reproduction, birth and lactation. Sex hormone disorders, also referred to as reproductive hormone disorders, medical conditions that affect the different glands and organs of the body responsible for the production of the sex hormones.

•  The sex hormones, which include testosterone (male) and estrogen (female) are substances that are essential in almost every body function, but more so in sexual functions and reproduction. Both testosterone and estrogen are present in males and females, but the levels differ according to sex. Males have higher levels of testosterone and females have higher levels of estrogen.

• Sex hormone disorders disrupt the normal production of hormones, which results in a reduced sex drive (libido), vaginal dryness, infertility, or excessive body hair, alopecia (hair loss) and may have long-term effects on metabolic, cardiovascular and bone health. 

Disorders of Sex Hormones in Females

• Polycystic Ovarian Syndrome (PCOS) This disorder is characterized by oligomenorrhea (irregular menstrual cycles) or amenorrhea (no menstrual cycles) with symptoms of hyperandrogenism (extra male like hormones) such as acne and hirsutism (extra male like hair growth). This is the most common endocrine disorder in young females. Blood tests which may be elevated in this condition are testosterone and DHEAS. The underlying cause of this, disorder is thought to be insulin resistance (poor response of body tissues to insulin). Therefore, blood sugar and insulin levels may also be evaluated. PCOS can result in obesity, infertility, diabetes, heart disease and uterine cancer. Exercise, weight loss and medications can be used to improve insulin sensitivity. Menstrual cycles can also be regulated with birth control pills.

• Amenorrhea: Amenorrhea is the absence of a menstrual period in a woman of reproductive age. It may be either primary (woman never developed menstrual periods) or secondary (absence of menstrual periods in a woman who was previously menstruating).

• Etiology: Primary amenorrhea is typically the result of a genetic or anatomic condition in young females that never develop menstrual periods (by age 16) and is not pregnant. Diseases of the pituitary gland and hypothalamus can also cause primary amenorrhea since these areas play a critical role in the regulation of ovarian hormones.

• Etiology: Pregnancy is an obvious cause of amenorrhea and is the most common reason for secondary amenorrhea. Other causes are varied and may include conditions that affect the ovaries, uterus, hypothalamus, or pituitary gland.

• Pathophysiology: Normally, the hypothalamus generates pulses of gonadotropin-releasing hormone (GnRH). GnRH stimulates the pituitary to produce gonadotropins (follicle-stimulating hormone and luteinizing hormone), which are released into the bloodstream. 

• Treatment:  Treatment of primary and secondary amenorrhea is determined by the precise cause. Treatment goals can be to relieve symptoms of hormonal imbalance, establish menstruation, prevent complications', and to achieve fertility.

• Dopamine agonists: In most women, treatment with dopamine agonists medications restores normal ovarian endocrine function and ovulation. e.g., Bromocriptine, or Pergolide are effective in treating hyperprolactinemia.

• Metformin: May used in women with polycystic ovary syndrome to induce ovulation. In premature ovarian failure, hormone therapy may be recommended both to avoid the unpleasant symptoms of estrogen depletion as well as prevent complications of low estrogen level such as osteoporosis.

• Hirsutism:  Hirsutism is the growth of excessive hair in a male pattern which include face, chest, abdomen and back and usually due to the increased production of androgens (male hormones). Disorders in which hirsutism are seen, include polycystic ovarian syndrome, congenital adrenal hyperplasia, ovarian tumors or adrenal tumors. Blood tests are used to help determine a cause. Occasionally, there is no cause found for the hair growth (idiopathic hirsutism). Medical treatment varies by the underlying cause of the hirsutism. Topical treatments including electrolysis and laser can be used to decrease hair growth.

Disorders of Sex Hormones in Males

• Hypogonadism:  Hypogonadism refers to the decreased production of testosterone. This can result from the pituitary gland not stimulating the testicles to make testosterone or the failure of the testicles to produce adequate testosterone. When testosterone levels are low, men can experience decreased libido (sex drive), erectile dysfunction, decreased energy, decreased muscle mass and thinning of the bones. Testicle size may also decrease, and sperm count decrease. Blood testing is done to diagnose hypogonadism and to determine the cause. MRI (magnetic resonance imaging) of the pituitary or testicular biopsy may be needed in some cases. Testosterone when low can be replaced by injection, patches or topical gels.

• Gynecomastia: The increase in breast tissue in a man is referred to as gynecomastia. This can occur during puberty and resolve on its own. Gynecomastia can also be due to medications, hypogonadism, thyroid disease, malnutrition, testicular cancers, adrenal cancers, liver disease or kidney disease. The cause of the gynecomastia is usually determined by physical exam, history and blood tests. Additional testing may include testicular ultrasounds or CT scan. 

• Causes ED can result from medical, physical or psychological factors. ED may be caused by a combination of factors that could also include medicine, alcohol or drugs. Intermittent ED is common. Many men experience occasional ED. It is generally caused by stress, exhaustion, or similar causes. Occasional ED should not be a cause of concern.

• Pathophysiology: From the mechanisms of a normal erection, erectile dysfunction may develop due to hormonal deficiency, disorders of the neural system, lack of adequate penile blood supply or psychological problems. 

• Other medications (Injectable Drugs) include: Apaverine, Alprostadil, and Phentolamine. These drugs are injected directly into the base of the penis. They have a direct effect on penile blood flow to achieve an erection.