Metabolic syndrome
Metabolic syndrome: Excerpt from Professional Guide to Diseases (Eighth Edition)
Metabolic syndrome — also called syndrome X, insulin resistance syndrome, dysmetabolic syndrome, and multiple metabolic syndrome — is a cluster of conditions characterized by abdominal obesity, high blood glucose (Type 2 diabetes mellitus), insulin resistance, high blood cholesterol and triglycerides, and high blood pressure. More than 22% of people in the United States meet three or more of these criteria, raising their risk of heart disease and stroke and placing them at high risk for dying of myocardial infarction.
In the normal digestion process, the intestines break down food into its basic components, one of which is glucose. Glucose provides energy for cellular activity, while excess glucose is stored in cells for future use. Insulin, a hormone secreted in the pancreas, guides glucose into storage cells. However, in people with metabolic syndrome, glucose is insulin-resistant and doesn’t respond to insulin’s attempt to guide it into storage cells. Excess insulin is then required to overcome this resistance. This excess in quantity and force of insulin causes damage to the lining of the arteries, promotes fat storage deposits, and prevents fat breakdown. This series of events can lead to diabetes, blood clots, and coronary events.
Causes
Abdominal obesity is a strong predictor of metabolic syndrome because intra-abdominal fat tends to be more resistant to insulin than fat in other areas. This increases the release of free fatty acid into the portal system, leading to increased apolipoprotein B, increased low-density lipoprotein (LDL), decreased high-density lipoprotein (HDL), and increased triglycerides. As a result, the risk of cardiovascular disease is increased.
Type 2 diabetes mellitus is a risk factor because a hallmark for metabolic syndrome is a fasting glucose level greater than 110 mg/dl. People with diabetes develop atherosclerotic heart disease at a younger age than other people. They’re also at increased risk of macrovascular disease (ischemic heart disease, stroke, and peripheral vascular disease). Diabetes is a coronary heart disease risk equivalent.
Insulin resistance and dyslipidemia are also risk factors because insulin resistance leads to hyperinsulinemia, hyperglycemia, abnormal glucose and lipid metabolism, damaged endothelium, and cardiovascular disease. Insulin is also responsible for reducing the amount of free fatty acids in the liver. However, people with insulin resistance have an increased amount of free fatty acids reaching the liver, resulting in high triglycerides and LDLs and producing an abnormal endothelium and atherosclerosis.
High blood pressure is a risk factor because the combination of insulin resistance, hyperinsulinemia, and abdominal obesity leads to hypertension and its harmful cardiovascular effects. Moreover, insulin resistance promotes salt sensitivity in people with high blood pressure.
Research also indicates that there may be a genetic predisposition to metabolic syndrome.
Signs and symptoms
Assessment commonly reveals a history of hypertension, abdominal obesity, sedentary lifestyle, poor diet, and a family history of metabolic syndrome. Physical findings include abdominal obesity (evidenced by a waist of more than 40" [101.6 cm] in men and 35"[88.9 cm] in women), blood pressure 130/85 mm Hg or higher, and a fasting blood glucose level that’s 100 mg/dl or higher. The patient may feel tired, especially after eating, and may have difficulty losing weight. If left untreated, such complications as coronary artery disease, diabetes, hyperlipidemia, and premature death may develop.
Diagnosis
Blood studies commonly indicate elevated blood glucose levels, hyperinsulinemia, and elevated serum uric acid. Use of lipid profile studies reveal elevated LDL levels, low HDL levels, and elevated triglycerides. Further diagnostic procedures are nonspecific, but may be performed to detect hypertension, diabetes, hyperlipidemia, and hyperinsulinemia.
Treatment
Lifestyle modification, focusing on weight reduction and exercise, is an important part of the treatment regimen. Modest weight reduction through diet and exercise considerably improves hemoglobin A1c levels, reduces insulin resistance, improves blood lipid levels, and decreases blood pressure — all elements of metabolic syndrome. Recent studies have shown that in patients with impaired glucose tolerance, losing an average of 7% of body weight reduced the risk of developing Type 2 diabetes by 58%.
To improve cardiovascular health, a diet rich in vegetables, fruits, whole grains, fish, and low-fat dairy products combined with regular exercise is recommended. Moreover, nutrient-dense, low-energy foodsshould replace low-nutrient, high-calorie foods. Meal replacements and shakes may also reduce risk factors for metabolic syndrome and improve weight loss. (SeeTherapeutic lifestyle change diet, page 908.)
A regular exercise program of moderate physical activity, in addition to dietary modifications, promotes weight loss, improves insulin sensitivity, and reduces blood glucose levels. According to the Surgeon General’s Report on Physical Activity and Health, a person should exercise moderately for a minimum of 30 minutes on most (if not all) days of the week. The selected exercise program should improve cardiovascular conditioning, increase strength through resistance training, and improve flexibility.
Medications may be used in the treatment of metabolic syndrome for patients who have a body mass index (BMI) of 27 kg/m2 or greater in the presence of other risk factors (such as diabetes, hypertension, and hyperlipidemia) or for patients with a BMI of 30 kg/m2 or greater without other risk factors. Weight loss medications may also be added to lifestyle changes if the patient hasn’t achieved significant weight loss after 12 weeks.
Pharmacologic treatment may also be indicated. Phentermine is used for short-term treatment of obesity in conjunction with diet and exercise. The only two medications that have been approved for long-term weight loss are orlistat and sibutramine. Orlistat works by decreasing the absorption of dietary fat by inhibiting pancreatic lipase, which is needed for fat breakdown and absorption. However, because absorption of fat-soluble vitamins is reduced, the patient may require vitamin supplementation. Studies show that when obese patients take orlistat in conjunction with dieting, they achieve greater weight loss and serum glucose control than by dieting alone. Sibutramine promotes weight loss by inhibiting the reuptake of serotonin, norepinephrine, and dopamine and increases the satiety-producing effects of serotonin. Further, it reduces the drop in metabolic rate that commonly occurs with weight loss.
Surgical treatment of obesity, such as through gastric bypass procedures, produces a greater degree and duration of weight loss than other therapies and improves or resolves most of the factors of metabolic syndrome. Candidates for surgical intervention include patients with a BMI greater than 40 kg/m2 or those with a BMI greater than 35 kg/m2 with obesity-related medical conditions. Gastric bypass procedures produce permanent weight loss in the majority of patients.
Special considerations
❑ Monitor the patient’s blood pressure, blood glucose, blood cholesterol, and insulin levels.
❑ Because research indicates that longer lifestyle modification programs are associated with improved weight loss maintenance, encourage patients with metabolic syndrome to begin an exercise and weight loss program with a friend or family member. Assist him in exploring options and support his efforts.
❑ To improve compliance, schedule frequent follow-up appointments with the patient. At that time, review his food diaries and exercise logs. Be positive and promote his active participation and partnership in his treatment plan.
Pictures
Book Source Details
- Book Title: Professional Guide to Diseases (Eighth Edition)
- Author(s): Springhouse
- Year of Publication: 2005
- Copyright Details: Professional Guide to Diseases (Eighth Edition), Copyright © 2005 Lippincott Williams & Wilkins.
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