Metabolic syndrome * is the name given to a group or cluster of conditions that occur together and increase a person's risk of diabetes * , heart disease, and stroke * . A short definition of the syndrome is that it is a group of metabolic * risk factors in one individual. Metabolic syndrome is also known as insulin resistance syndrome, syndrome X, and Reaven's syndrome, after the California diabetes researcher who first described it in 1992.
Enrique is a sixth-grade student in a California school whose family has a history of type 2 diabetes. Type 2 diabetes is a form of the disease that usually develops in adults whose bodies do not use the insulin * * , high blood pressure, and abnormal levels of cholesterol * in the blood. The risk of developing type 2 diabetes is also related to a person's race or ethnic group.
Enrique was asked to participate in a study of overweight Hispanic children to find out whether the high risk of type 2 diabetes in Hispanic adults affects younger Hispanics. Doctors have known for some years that Hispanic Americans, particularly those whose families came from Mexico, have a higher rate of diabetes than either African Americans or Caucasian Americans. Although researchers had studied overweight African American and Caucasian American children, they had not yet looked at Hispanic youth. The researchers wanted to test whether the definition of metabolic syndrome that was identified from studies of adults could be applied to children and teenagers.
Enrique was interested in finding out more about his health and the health of his relatives. He went with his parents to a clinic in the medical school nearby, where the doctors measured his height, weight, waistline, and blood pressure, and took samples of blood to see how well his body used insulin. They found that Enrique belonged in the 30 percent of overweight children who fit the pattern of metabolic syndrome and that he had a higher than average risk of developing type 2 diabetes as he grew into adulthood. The doctors gave Enrique and his parents some advice about nutrition and exercise to help Enrique lose weight, and some information about medications that can be given to children with insulin resistance. Enrique was not happy to have to cut down on some of his favorite foods, but he was glad that he learned more about his body, and that he helped the doctors learn more about his age group and ethnic community.
As the many names given to metabolic syndrome indicate, it has been defined somewhat differently by various public health organizations and medical societies since it was first named syndrome X by Gerald Reaven in 1992. Reaven was first concerned with the relationship of the syndrome to insulin resistance, a condition in which a person's body cannot effectively use the insulin produced by the pancreas * . Although insulin resistance is not considered a disease by itself, it is known to increase a person's risk of developing type 2 diabetes and heart disease. Reaven later wrote a book for the general public about the connection between syndrome X and heart disease.
To be diagnosed as having metabolic syndrome, an adult must have three or more of the following conditions:
A person can have only one of these health problems, but having any of them increases a person's risk of developing the others.
As Enrique's story indicates, doctors have asked whether children and adolescents can develop metabolic syndrome as well as adults. In early 2004, a group of researchers studied nearly 2,000 California youngsters over the age of 12 and found that two-thirds of the children had at least one abnormal metabolic measurement, and 10 percent had metabolic syndrome. The rate of metabolic syndrome climbed to 30 percent in children who were overweight or obese; this figure concerned researchers because the rate of overweight and obesity in American children tripled between the mid-1970s and the early 2000s. The doctors found that the rates of metabolic syndrome in children from different racial and ethnic groups follow the same pattern as those for adults: Hispanic children have the highest rates of metabolic syndrome, followed by Caucasian and African American children.
Using the standards proposed by the NCEP and AHA, it is estimated that about 34 percent of adults in the United States had metabolic syndrome as of 2016. But because the risk of developing the syndrome increases as people get older, some researchers suspected the true rate among American adults may be as high as 79 million people. Among Hispanic adults, it was thought to be as high as 36 percent. Researchers expected the rate to increase as the rate of obesity among children as well as adults continued to rise.
The causes of metabolic syndrome are not fully understood, although there is wide agreement that it is the end result of a complicated series of changes in the body's metabolism * * and environmental factors. Research continues to explore possible causes of metabolic syndrome in general and insulin resistance in particular.
Some people are more likely than others to develop metabolic syndrome. These risk factors include:
It is possible for people to develop metabolic syndrome over a period of years without any noticeable symptoms; this slow development is one reason why regular medical checkups are important to good health. In addition, some people develop metabolic syndrome without being obese or having a large waist measurement. Most people with metabolic syndrome are diagnosed in the course of a medical checkup that includes a blood test.
In some cases, people with diabetes that has not yet been diagnosed may notice increased thirst; increased urination, especially at night; unusual tiredness; and blurred vision. High blood pressure usually develops without any symptoms; a few people may notice dull headaches, dizzy spells, or more nosebleeds than usual.
Some people are diagnosed with insulin resistance, one of the risk factors for metabolic syndrome, because they develop a skin condition called acanthosis nigricans (ah-can-THO-sis NEE-grih-cans). A person with acanthosis nigricans develops dark patches on the skin of the neck or on the elbows, knees, knuckles, or armpits. This skin discoloration is more common in Hispanics or African Americans with insulin resistance.
Because metabolic syndrome usually does not have the kinds of symptoms that lead people to see a doctor, and because it is more likely to affect older adults, doctors recommend that adults be screened for the syndrome starting at age 45. If the results of blood tests and other measurements are normal, screening should be repeated only every three years. If the person has any risk factors in addition to age, screening should occur more frequently, with the frequency depending on the number of other risk factors and their severity.
Screening for metabolic syndrome consists first of measuring the patient's waist at the top of the upper edge of the hipbone just after the person has exhaled (breathed out). The doctor also weighs the patient, notes the distribution of body fat, and measures the patient's blood pressure. A sample of blood is taken and sent to a laboratory to measure the levels of triglycerides and cholesterol.
The patient's blood sugar level and possible insulin resistance can be tested in two ways. The first is a fasting blood glucose test. The person does not eat or drink anything (except water) after midnight the evening before the test and has a sample of blood drawn in the morning. The second test is called a glucose tolerance test and measures how quickly the body uses sugar. In this test, the person has one sample of blood drawn after fasting overnight and the second sample taken two hours after drinking a sugary liquid in the doctor's office or diagnostic laboratory. Blood sugar levels higher than normal but not high enough to indicate type 2 diabetes are considered a sign of prediabetes.
A prediabetes score on the fasting blood glucose test and the glucose tolerance test is considered indirect evidence of insulin resistance. To measure insulin resistance directly, a complicated test called the euglycemic (yoo-gly-SEEM-ik) clamp, which is usually done only in research laboratories, can be performed. The euglycemic clamp test takes about two hours. The patient is given an intravenous * Treatment
Metabolic syndrome is treated first with a combination of lifestyle changes. The goal is to lower the patient's risk of heart disease and type 2 diabetes by bringing blood pressure, blood sugar, and blood cholesterol down to healthier levels. If the patient has already been diagnosed with type 2 diabetes, treatment is focused on lowering the risk of heart disease. Specific lifestyle changes include:
Some patients need medications in addition to lifestyle changes to treat specific health risks associated with metabolic syndrome. The specific drugs prescribed and their dosages depend on the individual patient's test results:
Some risk factors for metabolic syndrome, such as age, race, and family history, cannot be changed. But people can lower their risk of developing metabolic syndrome by following guidelines from the National Heart, Lung, and Blood Institute:
Self-care at home for metabolic syndrome involves following the same recommendations as for preventive care.
See also Diabetes • Heart Disease: Overview • Hypertension • Obesity • Stroke
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Dichi, Isaias, and Andrea Name Colado Simao. Nutritional Intervention in Metabolic Syndrome. Boca Raton, FL: CRC Press, 2015.
Thompson, Dennis. “Metabolic Syndrome Increasingly Common: What Is It, and Why Worry?” CBS News. May 20, 2015. http://www.cbsnews.com/news/metabolic-syndrome-what-is-it-and-why-worry/ (accessed March 7, 2016).
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American Heart Association. 7272 Greenville Ave., Dallas, TX 75231. Toll-free: 800-242-8721. Website: http://www.heart.org (accessed March 7, 2016).
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* syndrome is a group or pattern of symptoms or signs that occur together.
* diabetes (dye-uh-BEE-teez) is a condition in which the body's pancreas does not produce enough insulin or the body cannot use the insulin it makes effectively, resulting in increased levels of sugar in the blood. High blood sugar can lead to increased urination, dehydration, weight loss, weakness, and a number of other symptoms and complications related to chemical imbalances within the body.
* stroke is a brain-damaging event usually caused by interference with blood flow to the brain. A stroke may occur when a blood vessel supplying the brain becomes clogged or bursts, depriving brain tissue of oxygen. As a result, nerve cells in the affected area of the brain, and the specific body parts they control, do not function properly.
* metabolic (meh-tuh-BALL-ik) pertains to the process in the body (metabolism) that converts food into energy and waste products.
* insulin is a hormone, or chemical produced in the body, that is crucial in controlling the level of glucose (sugar) in the blood and in helping the body use glucose to produce energy. When the body cannot produce or use insulin properly, a person must take synthetic insulin or other medications.
* obesity (o-BEE-si-tee) is an excess of body fat. People are considered obese if they weigh more than 30 percent above what is healthy for their height.
* cholesterol (ko-LES-ter-ol) is a fatlike substance found in the blood and body tissues.
* pancreas (PAN-kree-us) is the gland located behind the stomach that produces enzymes and hormones necessary for digestion and metabolism.
* triglycerides (try-GLISS-eh-rides) are a type of fatty substances found in the blood.
* plaque (PLAK) is a raised patch or swelling on a body surface. Arterial plaque occurs on the inner surface of an artery and is produced by fatty deposits.
* metabolism (meh-TAB-o-liz-um) is the process in the body that converts foods into the energy necessary for body functions.
* genetic (juh-NEH-tik) refers to heredity and the ways in which genes control the development and maintenance of organisms.
* gestational (jes-TAY-shun-al) means related to pregnancy.
* intravenous (in-tra-VEE-nus), or IV, means within or through a vein. For example, medications, fluid, or other substances can be given through a needle or soft tube inserted through the skin's surface directly into a vein.