ONE IN FIVE AMERICANS has metabolic syndrome, a major contributor to the development of vascular diseases and a disorder strongly associated with obesity, another growing health concern.1 In this article, I'll describe metabolic syndrome, how to recognize and manage it, and what your patient needs to know.
Three in one
Metabolic syndrome is a group of atherosclerotic cardiovascular disease risk factors with multiple causes that's closely linked to a generalized metabolic disorder previously called insulin resistance.2
The six components of metabolic syndrome, as defined by the American Heart Association (AHA), American Diabetes Association (ADA), and National Heart, Lung, and Blood Institute (NHLBI), are:
* abdominal obesity, characterized by increased waist circumference
* atherogenic dyslipidemia, characterized by a high triglyceride level and low high-density lipoprotein cholesterol (HDL-C) level
* insulin resistance or glucose intolerance, characterized by hyperglycemia despite increased plasma insulin levels. Impaired fasting glucose (defined as a fasting glucose level of 100 mg/dL to 125 mg/dL) or impaired glucose tolerance (defined as a 2-hour plasma glucose level of 140 mg/dL to 199 mg/dL), increase a patient's risk of developing type 2 diabetes, which in turn increases his risk for vascular diseases of the heart, brain, eyes, and kidneys.3,4
* prothrombotic state, characterized by high serum fibrinogen or plasminogen activator inhibitor levels
* high blood pressure (systolic BP of 130 mm Hg or more or a diastolic BP of 85 mm Hg or more). A systolic BP of 120 to 139 mm Hg or a diastolic BP of 80 to 89 is considered prehypertension.5
* proinflammatory state, characterized by elevated serum high-sensitivity C-reactive protein.6
What causes metabolic syndrome?
Obesity, physical inactivity, and genetic factors that can't be controlled are at the heart of metabolic syndrome. Some medications-including antidepressants, antipsychotics, corticosteroids, and benzodiazepines-also increase the risk for metabolic syndrome, because of their potential to cause weight gain.6
According to the AHA, a patient has metabolic syndrome if he has at least three of these risk factors:
* Waist circumference of 35 or more inches in women or 40 or more inches in men. A lower waist circumference cutoff (greater than 31 inches in women and greater than 35 inches in men) appears to be appropriate for Asian Americans, and patients of South Asian descent may have metabolic syndrome without excessive abdominal fat. Excess visceral fat is thought to have proinflammatory effects and may release harmful free fatty acids that may promote insulin resistance.2
* Triglyceride level of 150 mg/dL or more or receiving drug treatment for hypertriglyceridemia
* HDL cholesterol level of 50 mg/dL or less in women or 40 mg/dL or less in men, or receiving drug therapy for reduced HDL-C
* Blood pressure of 130 mm Hg or greater systolic or 85 mm Hg or greater diastolic, or receiving drug therapy for hypertension
* Fasting plasma glucose of 100 mg/dL or more, or receiving drug therapy for hyperglycemia.7
The diagnostic workup
If you suspect your patient has metabolic syndrome, obtain a patient history, including family, personal, and social history to evaluate for diabetes; coronary, cerebral, and peripheral vascular disease; and family history of early heart disease and diabetes. Perform medication reconciliation.
Ask the patient about his physical activity. If he has a sedentary lifestyle, ask about physical limitations or factors that might prohibit an increase in activity levels. You'll also want to identify physical, emotional, or social barriers to lifestyle changes that he'll need to make to treat metabolic syndrome. Perform a physical assessment.
Obtain the patient's age, baseline blood pressure, weight, height, and determine his body mass index (BMI). A BMI of 30 or higher indicates obesity; 25 to 29.9 is considered overweight, and below 25 is the goal (however, a BMI below 18.5 is considered underweight).
Take a waist measurement at the level of the iliac crest at end-expiration. Be aware that marginal increases in waist circumference (37 to 39 inches in men and 31 to 34 inches in women) put white, African-American, and Hispanic patients at increased risk for metabolic syndrome. Because the genetic contribution to insulin resistance is strong in these patients, suggest lifestyle changes to reduce risk.
Other diagnostic tests for patients suspected of metabolic syndrome include a fasting lipid panel to evaluate triglycerides, and fasting plasma glucose levels. For patients with normal fasting glucose levels, an oral glucose tolerance test may be performed to detect prediabetes. A 2-hour plasma glucose of 140 to 199 mg/dL after a 75-gram glucose load qualifies as prediabetes.4
Although lifestyle changes can effectively treat metabolic syndrome, predisposing genetic factors also must be identified and addressed. Management of metabolic syndrome is aimed at reducing weight and increasing activity, as these are the most effective interventions for decreasing insulin resistance and reducing abdominal circumference. The next therapeutic intervention is to initiate dietary changes to reduce fasting glucose and triglyceride levels and increase HDL cholesterol. Let's take a closer look:
* To combat central obesity, start the patient on a long-term weight loss plan. He should aim to lose 7% to 10% of total body weight over the first year, with continued slow weight loss thereafter until a BMI of 20 to 25 is reached. Rather than reducing calories drastically, he should reduce total daily caloric intake by 500 to 1,000 calories.2
* Increasing the patient's activity level can help reduce his risk of developing diabetes. The Finnish Diabetes Prevention Study found that the overall incidence of diabetes was reduced by 58% in patients whose lifestyle changes included weight loss, reducing dietary fat intake, increasing dietary fiber, and participating in moderate exercise for at least 30 minutes a day (walking, biking, skiing, jogging, or swimming). Study subjects also showed decreases in blood pressure and triglyceride levels.3 These results were similar to those found in the Diabetes Prevention Program Study, which looked at lifestyle changes vs. medication for reducing the incidence of type 2 diabetes.8 As with the Finnish study, subjects who made lifestyle changes had a 58% reduction in the incidence of diabetes. Subjects in the medication group had a 31% reduction in the development of diabetes.
* Blood pressure reduction may come about from making the recommended lifestyle changes, but if the patient's BP is still above 130/85 mm Hg, antihypertensive drugs may be prescribed to reduce the risk for vascular disease and heart failure. The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7), states that antihypertensive medications need to be prescribed for patients with BPs of 140/90 or greater (130/80 or greater for those with diabetes or kidney disease), and in patients for whom lifestyle changes haven't succeeded in reaching BP goals.5
* To correct dyslipidemia, lifestyle changes include replacing saturated fats with polyunsaturated fats such as corn, soybean, and sunflower oils, and monounsaturated fats such as canola, olive, and peanut oils. Advise the patient to eat fish twice a week and follow the Dietary Approaches to Stop Hypertension (DASH) diet to improve triglyceride and cholesterol levels. Drug therapy may be needed, such as with statins, fibrates, and niacin (nicotinic acid).
Fibrate drugs such as gemfibrozil and fenofibrate reduce triglyceride levels 20% to 50% and increase HDL cholesterol levels by 10% to 20%. Statins include atorvastatin and lovastatin. Niacin preparations such as niasprin improve HDL cholesterol levels by 15% to 35% and reduce triglyceride levels by 20% to 50%, but must be used cautiously and at lower doses in patients with diabetes because of the potential to increase blood glucose levels.7 Monitor the patient for muscle soreness, pain, and weakness, because fibrates and statins given in combination increase the patient's risk for myopathies.
Fighting inflammation and thrombosis
Blood levels of C-reactive proteins are elevated above 3 mg/L in patients with inflammatory processes, and are frequently elevated in patients with metabolic syndrome. Elevated C-reactive proteins double the patient's risk for coronary artery disease (CAD), and are thought to be associated with an increase in peripheral vascular disease and sudden death. Although evaluating C-reactive protein levels may help identify patients at a higher risk level for CAD and coronary events, research doesn't yet support specific treatments to reduce the inflammatory process.
To combat the prothrombotic state (characterized by increased levels of fibrinogen and plasminogen activator inhibitor-1), some patients with metabolic syndrome should take daily aspirin.9 The AHA recommends aspirin prophylaxis in most patients whose 10-year risk for heart disease is 10% or more, as determined by Framingham risk scoring. (For more information, see "Women and heart disease: What's new?" in the January issue of Nursing2008.) Including patients with metabolic syndrome whose 10-year risk for heart disease is 10% or more is appropriate.6
Follow-up for a patient with risk factors for metabolic syndrome depends on the type of treatment initiated. For example, a patient with prehypertension who makes lifestyle modifications should be reevaluated after 6 to 12 months. Patients with hypertension (or patients with prehypertension and diabetes) who are started on antihypertensive drugs should be seen in 1 to 2 weeks, then monthly until BP goals are met.5
Patients with an increased fasting plasma glucose, abdominal obesity, high triglycerides, or low HDL also should try lifestyle changes for 6 to 12 months. During this time, the patient should be able to reduce body weight by 7% to 10%, and also lower fasting glucose and triglyceride levels.
To help your patient understand metabolic syndrome and how to manage his care at home, give him the accompanying patient teaching sheet (see What you need to know about metabolic syndrome). By understanding metabolic syndrome and how to treat its various components, you can help your patient live a more healthful life and reduce his risk for complications.[black small square]
What you need to know about metabolic syndrome
Metabolic syndrome is a group of risk factors that increases your chance of developing heart disease, stroke, and diabetes. This syndrome may be caused by your body becoming less sensitive to insulin, which helps the body properly use blood sugar. Because you're less sensitive to insulin, your blood sugar levels rise, and you may develop diabetes. The exact cause of metabolic syndrome isn't known, but genetic factors, a sedentary (inactive) lifestyle, and a poor diet may play a role.
What are these risk factors?
If you have three or more of the following risk factors, you may have metabolic syndrome.
* A waistline of more than 40 inches for men or more than 35 inches for women
* A blood pressure of 130/85 mm Hg or higher
* A triglyceride level of 150 mg/dL or higher
* A fasting blood sugar level of 100 mg/dL or greater
* An HDL (good cholesterol) level less than 40 mg/dL in men or under 50 mg/dL in women
What are the symptoms of metabolic syndrome?
You may have no symptoms when you first develop metabolic syndrome. Later, however, you may develop signs and symptoms of heart disease, stroke, or diabetes. Because symptoms may not appear for months to years, talk to your health care provider if you have any of the risk factors listed above.
How can I take care of myself?
Because a sedentary lifestyle and obesity are the main risk factors that lead to the development of metabolic syndrome, getting more exercise and losing weight can help reduce or prevent complications. Follow your health care provider's instructions for gradually losing 7% to 10% of body weight over the first year. Reduce your dietary intake of saturated fats (as those found in animal fats), and eat more whole grains, legumes, fruits, and vegetables.
Participate in regular exercise, which can help you lose weight. Exercise also helps lower blood pressure and reduces your risk of developing diabetes-high blood pressure and diabetes increase your risk for developing metabolic syndrome.
If you smoke, stop. Smoking decreases blood levels of HDL (good cholesterol) and increases your risk for metabolic syndrome. Consume no more than one alcoholic drink a day for women or two drinks for men.
1. Cleveland Clinic Health Information Center. Metabolic syndrome. http://www.clevelandclinic.org/health/health-info/docs/3000/3057.asp?index=10783. Accessed December 11, 2007. [Context Link]
2. Grundy SM, et al. Diagnosis and management of the metabolic syndrome: An American Heart/National Heart, Lung, and Blood Institute Scientific Statement. Circulation. 112(17):2735-2752, October 25, 2005. [Context Link]
3. Tuomilihto J, et al. Prevention of type 2 diabetes mellitus by changes in lifestyle among subjects with impaired glucose tolerance. The New England Journal of Medicine. 344(18):1343-1350, May 3, 2001. [Context Link]
4. American Diabetics Association. What is pre-diabetes?http://www.diabetes.org/pre-diabetes.jsp. Accessed December 4, 2007. [Context Link]
5. National Institutes of Health. The seventh report of the joint national committee on prevention, detection, evaluation, and treatment of high blood pressure (JNC 7). (NIH Publication No. 04-5230). Washington, D.C.: U.S. Department of Health and Human Services, 2003. [Context Link]
6. Grundy SM, et al. Clinical management of metabolic syndrome: report of the American Heart Association/National Heart, Lung, and Blood Institute/American Diabetes Association conference on scientific issues related to management. Circulation. 109(4):551-556, February 3, 2004. [Context Link]
7. National Heart, Lung, and Blood Institute. Third report of the national cholesterol education program: Detection, evaluation, and treatment of high blood cholesterol in adults (ATP III). (NIH Publication No. 01-3670). Washington, D.C.: U.S. Department of Health and Human Services, 2001. [Context Link]
8. Knowler WC, et al. Diabetes Prevention Program Research Group. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. The New England Journal of Medicine. 346(6):393-403, February 7, 2002. [Context Link]
9. Fletcher B, Lamendola C. Insulin resistance syndrome. Journal of Cardiovascular Nursing. 19(5):339-345, September-October 2004. [Context Link]
American Heart Association. Your high blood pressure questions answered, metabolic syndrome.http://www.americanheart.org/presenter.jhtml?identifier=3025171. Accessed January 22, 2008.