What is a syndrome?

Causes and Symptoms

A syndrome is a collection of symptoms that characterize a disorder. For example, metabolic syndrome is the name given to a group of symptoms that warn of potential heart
disease, stroke, or diabetes. The symptoms of metabolic syndrome are obesity, high blood pressure, low levels of insulin, and high cholesterol.

Syndromes can be grouped into roughly fourteen categories: environmental (caused by the environment); congenital (existing at birth); gastrointestinal (affecting the stomach and intestines); cardiovascular (involving the heart and blood vessels); iatrogenic (induced by a treatment or procedure); neoplastic (caused by a malignant or benign tumor); endocrine (affecting glands, including sex glands); pulmonary (involving the lung); infectious (caused by a virus, bacterium, or fungus); renal (involving the kidneys); reticuloendothelial (affecting cells, including blood cells); neurological (affecting the nervous system); psychopathological (affecting the mind and behavior); and medically unexplained (cause uncertain).

The causes of syndromes vary. Some come from a single, clear source. For example, toxic shock syndrome
is caused by the bacterium Staphylococcus aureus. The bacterium enters the body through wounds from injuries or surgery incisions. It also breeds in superabsorbent tampons and contraceptive sponges. Symptoms of this syndrome include fever, headache, vomiting, diarrhea, and muscle aches.

Chinese restaurant syndrome is caused by monosodium glutamate (MSG), a chemical compound widely used to enhance the flavor of foods. MSG can induce headache, dizziness, giddiness, a feeling of facial pressure, tingling sensations over parts of the body, and chest pain.

Some syndromes result from any one of an array of causes. Fanconi syndrome, for instance, activates the release of certain substances from the kidney into the urine instead of the bloodstream. It can be caused by genetic defects, inherited diseases, exposure to heavy metals, a kidney transplant, or any number of medicines or diseases that damage the kidneys.

Other syndromes, such as carpal tunnel syndrome, arise from a combination of causes. This syndrome stems from increased pressure on certain nerves and tendons in the carpal tunnel in the wrist. Most people prone to carpal tunnel syndrome are born with a comparatively small carpal tunnel. This condition is complicated by injury to the wrist, an overactive pituitary gland, an underactive thyroid, rheumatoid arthritis, repeated use of vibrating hand tools, or overuse of the hands for activities such as typing.

The causes of some syndromes remain uncertain. For example, Reye syndrome
is a rapidly appearing, deadly disorder that affects all body organs, most seriously the brain and liver. It attacks adults but is primarily a children’s disease. Symptoms include personality changes, seizures, and loss of consciousness. There is no cure. The cause is unknown, but there seems to be a link to the use of aspirin taken for a previous viral disease.

Restless legs syndrome
is the nighttime twitching of the legs that often leads to insomnia. The cause is unknown, but there seems to be some connection to a family history of the disorder. Also associated with this syndrome are anemia, diabetes, kidney failure, and certain prescription and nonprescription medicines.

Just as the causes vary, so too do the number and severity of symptoms, depending on the syndrome. Barrett’s esophagus, for example, is a condition in which the esophagus (the tube that carries food to the stomach) develops new cells similar to those found in the intestines. Symptoms are nonexistent, and the cause is unknown. It can, however, lead to a deadly type of esophageal cancer.

The symptoms of premenstrual syndrome (PMS) vary widely in number and severity from woman to woman. Some women experience few symptoms; others need several days of bed rest. Symptoms include irritability, headache, backache, weight gain, swelling or tenderness of the breasts, depression, fatigue, and loss of sex drive.

Some fifty different symptoms, or characteristics, are associated with Down syndrome. Characteristics include intellectual disabilities; short stature; slow physical growth; weak muscles; short, stocky arms and legs; a wide space between the big toe and second toe; small, low-set ears; a narrow roof of the mouth; crooked teeth and other dental problems; heart defects; an underactive thyroid; and hearing problems. So many symptoms require a lifetime of care.

Asperger syndrome
produces no symptoms that require medical attention, but people with this autism spectrum disorder display abnormal behaviors and have limited social skills that can bring on unwanted consequences, such as being shunned by others. Some people with this syndrome seem “normal” most of the time. Others just seem odd or different from other people, quieter and disinterested. Still others exhibit somewhat bizarre, or at least socially unacceptable, behaviors, such as inflexible routines, a narrow but intense focus of interests, an inability to empathize with other people, and difficulty understanding some types of humor, especially teasing and sarcasm. Yet they are often above average in intelligence and do no more harm than so-called normal people. The odd behaviors lead people to think that Asperger syndrome is a mental disorder. In fact, it is a type of autism, a developmental disability that affects how the brain processes information. The cause is unknown.

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