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Nursing:
doi: 10.1097/01.NURSE.0000387152.77867.8c
Feature: CE Connection

Sounding the alarm about metabolic syndrome

Bolton, Margaret M. BSN, ANP-C, BC-ADM, CDE

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Author Information

Margaret M. Bolton is director of the endocrine intensive insulin program in the department of endocrinology and metabolism at Ochsner Medical Center in New Orleans, La.

The author has disclosed that she has no financial relationships related to this article.

ANY HEALTH PROBLEM that affects a third of American adults is sure to impact your nursing practice. Metabolic syndrome, a growing and commonly silent condition, poses a significant public health crisis. Left unchecked, it could have a staggering effect on healthcare in the United States in the years ahead. This article explores how to recognize this complex condition and teach patients how to manage it.

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Cluster of risks

The term metabolic syndrome describes a cluster of metabolic risk factors in one person that are believed to have a direct effect on atherosclerotic disease:

* central obesity (excess body fat in the abdomen associated with an enlarged waist circumference)

* hypertension

* dyslipidemia

* dysglycemia.

The underlying cause of metabolic syndrome and the specific diagnostic criteria used to identify it remain a matter of debate. What scientists do agree on is the need to identify patients at high risk for early morbidity and mortality from both cardiovascular disease (CVD) and type 2 diabetes before they develop one or both conditions.1

In the United States, CVD is the leading cause of death among both men and women2 and the presence of type 2 diabetes doubles the risk. In fact, over 50% of deaths in patients with type 2 diabetes are due to CVD.3 People with metabolic syndrome have a significantly greater risk of CVD, particularly men over age 45 and women over 55. These people also have a fivefold risk of developing type 2 diabetes.1,4

National statistics reveal that an alarming 34% of Americans over age 20 meet the criteria for metabolic syndrome. The incidence has risen in tandem with the prevalence of overweight and obesity in this country. The National Health and Nutrition Examination Survey estimates that 64% of adults and 15% of children and adolescents are either overweight or obese.5

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One cause or many?

Some researchers believe that a single metabolic defect is responsible for metabolic syndrome; others believe that a constellation of risk factors together cause the problem. Let's consider the evidence under debate.

Is insulin resistance alone responsible? Some researchers believe that a single metabolic defect is at the root of metabolic syndrome. Insulin resistance is a defect in the ability of the body's cells, particularly skeletal muscle, liver, and adipose tissue, to respond normally to insulin. In the initial stages of insulin resistance, beta cells in the pancreas hypertrophy and produce more insulin to compensate (hyperinsulinemia). Over time, though, they can't sustain this process and eventually fail, diminishing insulin production. This disruption in normal glucose regulation is thought to unleash a host of negative metabolic consequences, including type 2 diabetes, obesity, hypertension, dyslipidemia, and a proinflammatory, prothrombotic environment that increases the risk of CVD.1

Are multiple factors at play? Those who view metabolic syndrome as having multiple causes consider factors such as sedentary lifestyle, genetic predisposition, advancing age, smoking, and an atherogenic diet at the root of the problem. They suspect that these conditions lead to metabolic risk factors of insulin resistance, hypertension, and dyslipidemia, which in turn pose a high risk of CVD and type 2 diabetes if left untreated.

Whether metabolic syndrome is the result of one defect or a group of risk factors working in tandem is the subject of ongoing research. However, researchers agree that the presence of multiple risk factors in one patient creates a higher-than-normal risk of complications and death related to type 2 diabetes and CVD.

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Pinpointing clinical criteria

The best approach to combating metabolic syndrome is to think of it as a continuum and aim for diagnosis and management before the patient progresses to CVD or type 2 diabetes. A systematic approach is important. Of several available definitions for metabolic syndrome, the one most commonly used in the United States was developed by the National Cholesterol Education Program's Adult Treatment Panel III.6 Pinpointing five diagnostic criteria, it calls for measurement of BP, waist circumference, a fasting lipid panel, and a fasting plasma glucose (FPG) level. Anyone meeting three of the five criteria at any time is considered to have metabolic syndrome. See Three of five makes the grade for key values.

A patient with metabolic syndrome who doesn't have type 2 diabetes or CVD should undergo risk stratification. One approach is the Framingham risk assessment tool designed to compute the 10-year risk of myocardial infarction and coronary death. Available in print, online, and in personal digital assistant format, this tool incorporates other known CVD risk factors and stratifies risk by percentage.6,7

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Uncovering problems

Someone who doesn't meet the diagnostic criteria for metabolic syndrome may nevertheless be in the early stages. With a careful history and physical assessment, you might detect one or more individual components of the syndrome that could move the patient further along the continuum. The focus of your evaluation should include assessment and collection of the following baseline data:

* severity of individual components of the syndrome and the presence of associated comorbid conditions, such as central obesity, hypertension, dyslipidemia, type 2 diabetes, gout, obstructive sleep apnea, polycystic ovarian syndrome, and fatty liver

* lifestyle risk factors: diet, physical activity, and smoking status

* medication history with particular attention to drugs that may contribute to insulin resistance (glucocorticoids, niacin, protease inhibitors, cyclosporine)8

* psychosocial data: support systems, finances, time constraints, life stressors.

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Recognizing the red flags

To determine a patient's risk of metabolic syndrome (and therefore of CVD and type 2 diabetes), assess these clinical measures.

Obesity and central obesity. Body mass index (BMI), which is calculated from a person's height and weight, is an indirect but reliable measure of body fatness. A patient whose BMI is 25 to 29.9 is considered overweight; anyone with a BMI of 30 and above is considered obese.9 The higher a patient's BMI, the more likely the patient has comorbid conditions that may need further evaluation and treatment, such as type 2 diabetes, hypertension, and dyslipidemia.

Current guidelines recommend that clinicians also routinely measure waist circumference during the physical exam. Because an enlarged waist circumference indicates central obesity, it provides more focused information about a patient's risk of metabolic syndrome. For most adult Americans, the cutoff for elevated waist circumference is at least 102 cm for men and at least 88 cm for women. The cutoffs are slightly lower for ethnically Asian adults: 90 cm for men and 80 cm for women.10

Hypertension. Usually asymptomatic, hypertension can cause target organ damage, including retinopathy, heart failure, stroke, chronic kidney disease, and peripheral arterial disease if untreated. Someone with severe elevations in BP (higher than 180/110 mm Hg) without progressive target organ dysfunction (hypertensive urgencies) may experience severe headache, shortness of breath, epistaxis, or severe anxiety. Hypertensive emergencies are characterized by severely elevated BP (higher than 180/120 mm Hg) complicated by evidence of impending or progressive target organ dysfunction, such as unstable angina, acute myocardial infarction, and acute left ventricular failure with pulmonary edema.11

Insulin resistance, prediabetes, or diabetes. One of the most common signs of insulin resistance is acanthosis nigricans, a patchy, velvety brown hyperpigmentation of the skin commonly noted around the neck and in the axillae, but also seen at the elbows, knees, and knuckles. It's probably due to the effect of high circulating insulin levels on insulin-like growth factor receptors in the skin.8 A common symptom of insulin resistance is fatigue ranging from feelings of decreased energy to exhaustion and depression. Drowsiness after meals, especially meals high in carbohydrates, is common.

Figure. Signs of Tro...
Figure. Signs of Tro...
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Hyperinsulinemia also may produce signs and symptoms related to hypoglycemia, including confusion, diaphoresis, and tremors; eating generally relieves these feelings. A patient with these signs and symptoms should undergo an endocrine workup to rule out underlying endocrine disorders including Cushing syndrome, acromegaly, pheochromocytoma, lipodystrophy, hemochromatosis, glucagonoma, and polycystic ovarian disease.12

Hyperglycemia that doesn't meet the diagnostic criteria for diabetes is classified as either impaired fasting glucose (IFG) or impaired glucose tolerance (IGT). Both are considered prediabetes, or a risk factor for future diabetes. IFG is defined as a FPG of 100 to 125 mg/dL; IGT is defined as a 2-hour plasma glucose value in the oral glucose tolerance test of 140 to 199 mg/dL. Associated with obesity, hypertension, and dyslipidemia with high triglycerides and/or low high-density lipoprotein (HDL) cholesterol, both IFG and IGT are risk factors for future diabetes.13

The cardinal signs and symptoms of undiagnosed and uncontrolled type 2 diabetes are polydipsia, polyphagia, polyuria, nocturia, paresthesias, unexplained weight loss, fatigue, and blurred vision. In its 2010 Clinical Practice Recommendations, the American Diabetes Association (ADA) recommends the use of hemoglobin A1C (A1C) to diagnose diabetes and prediabetes (now categorized as increased risk of future diabetes). An A1C range of 5.7% to 6.4% indicates increased risk of future diabetes, and an A1C equal to or above 6.5% is considered diabetes.13

Dyslipidemia. Although lab work is necessary to detect lipid abnormalities, you may find physical signs commonly associated with high circulating levels of phospholipids. For example, arcus cornealis, also known as corneal arcus, a thin grayish-white arc or circle at the edge of the cornea common in older adults, may occur prematurely in someone with dyslipidemia. Xanthelasma, which may also signal dyslipidemia, are yellowish, slightly raised, well-circumscribed plaques in the skin usually found along the nasal portions of one or both eyelids.

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Strategies to help your patient

Despite the uncertainty about causes of metabolic syndrome, the American Heart Association/National Heart, Lung, and Blood Institute (AHA/NHLBI) has issued clear-cut management approaches based on the severity of CVD risk.4 Therapeutic lifestyle changes are the cornerstone of treatment. (See Setting therapeutic goals.)

If your patient has been identified as being on the metabolic syndrome continuum, clarify the associated health implications and encourage the patient to follow recommended treatments.

* Explain what metabolic syndrome is and why it's a risk factor for diabetes and CVD.

* Provide education, support, and motivation for important behavioral changes including smoking cessation, weight reduction, increased physical activity, and dietary modifications. For example, ask what strategies the patient has tried before to lose weight and what did or didn't work. Offer information about weight loss programs if appropriate. Also inquire about the patient's diet and help identify ways to overcome barriers to healthy eating. If the patient travels frequently (for business, for example), making a plan for healthy eating on the road may help the patient improve eating habits.

* If indicated, involve case management to help the patient overcome financial barriers to achieving therapeutic goals, such as finding affordable healthcare and assistance with medications.

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Promising future?

A clearer understanding of metabolic syndrome, plus new management techniques under development or in early use, could help clinicians manage metabolic syndrome even better in the future.

Consensus on criteria for metabolic syndrome. The ongoing debate among healthcare organizations worldwide has complicated the process of identifying patients with metabolic syndrome. A single definition would lead to earlier identification and treatment.

A polypill. Patients who need multiple medications are less likely to adhere to treatment. Using a combination drug, or polypill, containing an antihypertensive agent and antidyslipidemic agent, aspirin, and vitamin supplements could decrease cardiovascular events by 80% in at-risk patients. A large, randomized trial to assess the effectiveness and tolerability of a polypill to treat patients with cardiac risk factors is currently underway. Early results are promising, but numerous regulatory, financial, and clinical challenges remain to be sorted out.14

Weight-reduction drugs. Sibutramine and orlistat, the only weight-loss drugs currently approved by the FDA, have been found to reduce body weight when combined with weight-loss diets. However, both can cause adverse reactions and sibutramine is now contraindicated in patients with a history of CVD.15,16

Multiple gastrointestinal (GI) hormones and peptides may have potential as antiobesity agents, but none has FDA approval for that purpose. For example, exenatide (Byetta) and pramlintide (Symlin), approved for treatment of diabetes, both result in modest weight loss along with their antihyperglycemic properties. Pharmaceuticals derived from GI hormones will continue to be investigated for potential use in preventing and treating obesity.17

Bariatric surgery. The two most common approaches to weight-loss surgery in the United States are gastric banding and gastric bypass. Both procedures create a smaller stomach pouch to reduce the amount of food a person can comfortably eat, resulting in earlier satiety, decreased caloric intake, and weight loss. Both procedures require patients to exercise and manage their caloric intake to maintain weight loss over the years. They also need ongoing vitamin and mineral supplementation due to decreased absorption through the truncated GI tract.

Gastric banding, a simpler, reversible procedure compared with bypass, results in permanent reconfiguration of the stomach and small intestine. But bypass may have a significant advantage for patients with preexisting type 2 diabetes. For reasons that are still unknown, gastric bypass results in resolution of diabetes immediately after surgery, even before any weight loss occurs.18

Pending long-term safety and efficacy studies, the ADA has been conservative in its recommendations regarding bariatric surgery. For now, weight-loss surgery is recommended only for patients with type 2 diabetes and a BMI of greater than or equal to 35. As more research is done on the safety and efficacy of these surgical procedures, more people may be able to take advantage of this treatment option.

Insurance health programs. Many private insurers have started offering discounts to people with healthy lifestyles. They encourage and reward routine physical exams, regular recommended screenings, control of modifiable risk factors such as weight and smoking, and treatment to appropriate goals for metabolic risk factors such as hypertension and dyslipidemia.

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Holding the key to better health

Help reduce the hazards of metabolic syndrome by uncovering silent health problems and addressing your patients' unhealthy behaviors. By doing so, you can put the key to managing this dangerous disorder in your patients' hands.

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Three of five makes the Grade4,10

The diagnosis is metabolic syndrome if three or more of these factors are present at any time in the patient's medical history.

Elevated waist circumference:

* 40 inches (102 cm) or more in men (non-Asian origin)

* 35 inches (88 cm) or more in women (non-Asian origin)

* 90 cm or more in men; 80 cm or more in women (both East Asians and South Asians)

Elevated triglyceride level (fasting):

* 150 mg/dL or greater or on medication for elevated triglycerides

Reduced HDL cholesterol level:

* less than 40 mg/dL in men

* less than 50 mg/dL in women

* or on medication for reduced HDL-cholesterol

Elevated BP:

* 130 mm Hg systolic or more or 85 mm Hg or more diastolic

* or on antihypertensive medication

Elevated fasting blood glucose level:

* 100 mg/dL or more

* or on medication for elevated blood glucose

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REFERENCES

1. Lorenzo C, Williams K, Hunt KJ, Haffner SM. The National Cholesterol Education Program - Adult Treatment Panel III, International Diabetes Federation, and World Health Organization definitions of the metabolic syndrome as predictors of incident cardiovascular disease and diabetes. Diabetes Care. 2007;30(1):8–13.

2. Centers for Disease Control and Prevention. Heart disease facts and statistics. http://www.cdc.gov/heartDisease/statistics.htm.

3. National Diabetes Information Clearinghouse. National diabetes statistics, 2007. http://diabetes.niddk.nih.gov/dm/pubs/statistics/#deaths.

4. Grundy SM, Cleeman JI, Daniels SR, et al. Diagnosis and management of the metabolic syndrome: an American Heart Association/National Heart, Lung, and Blood Institute Scientific Statement. Circulation. 2005;112(17):2735–2752.

5. Ervin RB. Prevalence of metabolic syndrome among adults 20 years of age and over, by sex, age, race and ethnicity, and body mass index: United States, 2003–2006. Natl Health Stat Report. 2009;(13):1–7.

6. ATP III guidelines at-a-glance quick desk reference. http://www.nhlbi.nih.gov/guidelines/cholesterol/atglance.pdf.

7. National Cholesterol Education Program. Risk assessment tool for estimating your 10-year risk of having a heart attack. http://hp2010.nhlbihin.net/atpiii/calculator.asp.

8. Olatunbosun ST, Dagogo-Jack S. Insulin resistance. eMedicine. http://emedicine.medscape.com/article/122501-print.

9. Centers for Disease Control and Prevention. About BMI for adults. http://cdc.gov/healthyweight/assessing/bmi/adult_BMI/index.html.

10. Rosenzweig JL, Ferrannini E, Grundy SM, et al. Primary prevention of cardiovascular disease and type 2 diabetes in patients at metabolic risk: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab. 2008;93(10):3671–3689.

11. National Heart, Lung, and Blood Institute. The seventh report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7). http://www.nhlbi.nih.gov/guidelines/hypertension/.

12. Mantzoros C. Insulin resistance: definition and clinical spectrum. Up-to-Date. 2005. http://www.uptodate.com.

13. American Diabetes Association. Summary of revisions for the 2010 clinical practice recommendations. Diabetes Care. 2010;33(suppl 1):S3.

14. Guglietta A, Guerrero M. Issues to consider in the pharmaceutical development of a cardiovascular polypill. Nat Clin Pract Cardiovasc Med. 2009;6(2):112–119.

15. Food and Drug Administration. Meridia (sibutramine hydrochloride): follow-up to an early communication about an ongoing safety review. http://www.fda.gov/Safety/MedWatch/SafetyInformation/SafetyAlertsforHumanMedicalProducts/ucm198221.htm.

16. Siebenhofer A, Horvath K, Jeitler K, et al. Long-term effects of weight-reducing drugs in hypertensive patients. Cochrane Database Syst Rev. 2009;8(3):CD007654.

17. Neary MT, Batterham RL. Gut hormones: implications for the treatment of obesity. Pharmacol Ther. 2009;124(1):44–56.

18. Dixon JB, O'Brien, PE, Playfair J, et al. Adjustable gastric banding and conventional therapy for type 2 diabetes: a randomized controlled trial. JAMA. 2008;299(3):316–323.

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RESOURCES
Alberti KGMM, Eckel RH, Grundy SM, et al. Harmonizing the metabolic syndrome: a joint interim statement of the International Diabetes Federation Task Force on Epidemiology and Prevention; National Heart, Lung, and Blood Insitute; American Heart Association; World Heart Federation; International Atherosclerosis Society; and International Association for the Study of Obesity. Circulation. 2009;120:1640–1645

Centers for Disease Control and Prevention: Division for Heart Disease and Stroke Prevention. A public health action plan to prevent heart disease and stroke. http://www.cdc.gov/DHDSP/library/action_plan/.

© 2010 Lippincott Williams & Wilkins, Inc.

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