The Endocrine System - Ailments: what can go wrong with the endocrine system

As much as 10 percent of the population will experience some endocrine disorder in their lifetime. Most endocrine disorders are caused by an increased

A chart tracking changing hormone levels during an average ovarian cycle. (Illustration by

Hans & Cassady

.)

or decreased level of particular hormones. Tumors (abnormal tissue growth) in endocrine glands are one of the major causes of hormone overproduction. Hormone underproduction is often due to defective receptors on cells. The result is that the cells fail to notify an endocrine gland when production of its particular hormone is too low. Injury to or disease of an endocrine gland can also result in low hormone levels.

The following are just a few of the many disorders that can result from an improperly functioning endocrine system.

Acromegaly and gigantism

Acromegaly is a disorder in which the anterior pituitary produces too much growth hormone (GH). This causes an increased growth in bone and soft tissue, especially in the extremities—nose, jaw, fingers, and toes. If the disorder occurs in children who have not yet fully developed, the increased levels of GH also result in the exceptional growth of the long bones. This condition, a variation of acromegaly, is known as gigantism.

Acromegaly is a rare disorder, occurring in approximately 50 out of every 1 million people. Both men and women are affected. Because the symptoms come on gradually, the disorder is often not identified until the patient is middle aged.

In 90 percent of the cases, acromegaly is caused by a noncancerous tumor that develops within the pituitary. The tumor causes the anterior pituitary to ignore growth hormone inhibiting hormone (GHIH), a regulating hormone secreted by the hypothalamus that stops the pituitary from producing GH. GH is thus secreted without a stopping mechanism.

The first step in treating acromegaly is the surgical removal of the tumor. Afterward, some patients often require medications that help to reduce the secretion of GH. With treatment, an individual suffering from acromegaly may be able to live a normal life span. Without treatment, an individual will most likely die early because of the disorder's adverse effects on the heart, lungs, and brain.

Addison's disease

Addison's disease is a disorder in which the adrenal cortex produces too little cortisol and aldosterone, resulting in the disruption of numerous bodily functions. About 4 in every 100,000 people suffer from this disorder. It strikes men and women of all ages.

The most common cause of Addison's disease is the destruction or shrinking of the adrenal cortex. In about 70 percent of the cases, this is caused by an autoimmune disorder: a condition in which the body produces antibodies that attack and destroy the body's own tissues instead of foreign invaders such as viruses and bacteria. In the case of Addison's disease, antibodies attack and destroy cells of the adrenal cortex.

Addison's disease tends to be a gradual, slowly developing disease. By the time symptoms are noted, about 90 percent of the adrenal cortex has been destroyed. The most common symptoms include fatigue and loss of energy, decreased appetite, nausea, vomiting, diarrhea, abdominal pain, muscle weakness, dizziness when standing, and dehydration. Unusual areas of darkened skin and dark freckling also appear. Women suffering from the disease may stop having normal menstrual periods. As the disease progresses, the symptoms become more severe: abnormal heart rhythms, uncontrollable nausea and vomiting, a drastic drop in blood pressure, kidney failure, and unconsciousness.

Individuals suffering from Addison's disease are treated with steroid medications that replace cortisol and aldosterone in the body. Taking these medications for the rest of their lives, those individuals can expect to live a normal life span.

Cushing's syndrome

Cushing's syndrome is a disorder caused by an overproduction of steroids—mostly cortisol—by the adrenal cortex, resulting in obesity and muscular weakness. The disorder occurs in about 15 out of every 1 million people per year. It usually strikes adults (men and women) between the ages of twenty and fifty.

Cushing's syndrome can be caused by a tumor either in the pituitary gland or in one of the adrenal glands. The anterior pituitary secretes adrenocorticotropic hormone (ACTH), which stimulates the adrenal cortex to release cortisol. A tumor in the pituitary causes the overproduction of ACTH, which in turn causes the overproduction of cortisol. This is the most common cause. A tumor in the adrenal glands can also lead to the overproduction of cortisol by the adrenal cortex.

The following are some of the symptoms that appear when cortisol is produced in excess: abnormal weight gain (resulting especially in a round or "moon" face), purple and pink stretch marks across the abdomen and sides, high blood pressure, weak bones and muscles, low energy, mood swings and depression, and abnormal hair growth on the face in women.

Treatment for Cushing's syndrome includes the surgical removal of either the pituitary tumor or the adrenal tumor. After surgery, some patients are also given drugs that help decrease cortisol production. If a patient's entire adrenal gland is removed, the patient will have to take steroid medications for the rest of his or her life.

A woman suffering from Cushing's syndrome, a disorder caused by an overproduction of steroids. (Photograph courtesy of John Radcliff Hospital. Reproduced by permission of

Photo Researchers, Inc.

)

Diabetes mellitus

Diabetes mellitus (commonly referred to simply as diabetes) is a disorder in which the cells of the body cannot absorb glucose. This condition is brought about either because the pancreas no longer produces enough insulin or because the cells do not respond to the effects of the insulin that is produced. Approximately 14 million Americans—about 5 percent of the population-have diabetes, and almost 50 percent of them are unaware they have it. Some 300,000 people in the United States die each year from the disorder.

Common symptoms of diabetes include frequent urination, excessive thirst, tiredness, weight loss, hunger, and slow wound healing. The long-term effects of diabetes include loss of vision decreased blood supply to the hands and feet, and pain. If left untreated, the disorder can lead to kidney failure, heart disease, stroke, coma, and death. There are two types of diabetes mellitus: Type I diabetes and Type II diabetes.

Type I diabetes, sometimes called juvenile diabetes, begins most commonly in childhood or adolescence. In this form of diabetes, the pancreas produces little or no insulin. Scientists believe that Type I diabetes may be brought about by a virus or microorganism that trigger's an autoimmune disorder: antibodies that normally destroy foreign invaders end up destroying the islets of Langerhans, the pancreatic cells that produce insulin.

The disorder can be controlled with daily injections (using a small needle and a syringe) of insulin. A strict diet must also be followed. Too little food (or eating too late to coincide with the action of the injected insulin), alcohol, or increased exercise can all lead to low blood sugar levels. A diabetic (person suffering from diabetes) may then become cranky, confused, tired, sweaty, and shaky. If untreated, the diabetic can lose consciousness and have a seizure. Before the condition becomes too serious, the diabetic should have something sweet to eat or drink like candy, sugar cubes, juice, or some other high-sugar snack to balance his or her sugar levels.

Type II diabetes, sometimes called adult-onset diabetes, is the more common form of diabetes. More than 90 percent of the diabetics in the United States suffer from this form. It occurs most often in people who are overweight and who do not exercise. It is also more common in Native Americans, Hispanic Americans, and African Americans.

In Type II diabetes, the pancreas may produce enough insulin, but the body's cells have become resistant to the effects of insulin. Age, obesity (more than 20 percent above ideal body weight), and a family history of diabetes all play a role in the cause. The symptoms of Type II diabetes can begin so gradually that a person may not know they suffer from the disorder. Sometimes the symptoms can develop over several years in overweight adults over the age of forty.

As is the case for Type I diabetes, there is no cure for Type II diabetes. Treatment focuses on keeping blood glucose levels within the normal range. For many Type II diabetics, weight loss is an important goal in helping to control their diabetes. Moderate exercise and a well-balanced, nutritious diet are key steps. To keep blood glucose levels from surging too high, food intake must be distributed over the course of an entire day. For some Type II diabetics, medications are available to help lower blood glucose levels.

Hyperthyroidism

Hyperthyroidism is a disorder in which an overactive thyroid gland produces too much thyroxine. It generally results from a tumor of the thyroid. It can also be brought about by an autoimmune disorder in which antibodies bind to the thyroid cells, forcing them to produce excessive amounts of thyroxine. This latter form of hyperthyroidism is known as Graves' disease.

Regardless of the form, hyperthyroidism has the same symptoms: weight loss with increased appetite, shortness of breath, nervousness and anxiety, rapid heart beat, weak muscles, intolerance of heat, and difficulty relaxing and sleeping. In addition, the eyes may bulge and the thyroid may be visibly enlarged (a condition known as a goiter).

Treatment for hyperthyroidism may include the surgical removal of the thyroid tumor (if one is present) or part of the thyroid. Since the thyroid is the only body part that absorbs iodine, radioactive iodine may be administered to destroy the hormone-producing cells and shrink the enlarged gland. Medications to decrease or block the production of thyroxine may also be given. With proper treatment, most individuals suffering from hyperthyroidism can lead normal lives.

Hypothyroidism

Hypothyroidism is a disorder in which an underactive thyroid gland fails to produce or secrete as much thyroxine as the body needs. Since thyroxine is essential to physical growth and body metabolism, a low supply of this hormone can slow life-sustaining processes and damage organs and tissues in every part of the body.

The disorder is one of the most common chronic (long-term) diseases in the United States. As many as 11 million adults and children may be affected by hypothyroidism. Women are twice as likely as men to suffer from the disorder.

Hypothyroidism is most often the result of Hashimoto's disease. In this disease, the body's defense system fails to recognize that the thyroid gland is part of the body's own tissues and attacks it as if it were a foreign body. Sometimes the gland is destroyed in the process. Infections caused by viruses and bacteria and a diet lacking iodine can also bring about hypothyroidism.

Symptoms, which may not appear until years after the thyroid has stopped functioning, include fatigue, decreased heart rate, weight gain, depression, muscle pain or weakness, dry skin, extreme sensitivity to pain, and puffiness of the face.

If hypothyroidism occurs in early childhood, the condition is known as cretinism. This condition results in dwarfism: the head and trunk, which should be about the same length as the legs, grow about one-and-a-half times larger. Cretins (those suffering from cretinism) have scanty hair and very dry skin. They are often mentally retarded. However, if the condition is discovered early enough and medications to replace thyroxine are given, mental retardation and other symptoms can be prevented.

Synthetic or man-made thyroid hormone medications are also given to adults to treat hypothyroidism. This treatment generally maintains normal thyroid hormone levels, allowing an individual to lead a normal lifestyle.