Metabolic Syndrome

Metabolic syndrome is the name for a group of risk factors linked to obesity that increase the chance for heart disease, as well as for other health problems such as diabetes and stroke. The term "metabolic" refers to the normal biochemical processes involved in the body's production of energy. In this article, "heart disease" refers to coronary artery disease (atherosclerosis of the arteries that supply the heart).

Metabolic syndrome is made up of a group of factors that can increase risk even if they are only moderately raised (borderline high-risk factors). The syndrome itself usually has no symptoms. Most of the risk factors linked to metabolic syndrome have no signs or symptoms, although a large waistline is a visible sign.

Other Names

• Syndrome X
• Insulin resistance syndrome
• Dysmetabolic syndrome
• Hypertriglyceridemic waist
• Obesity syndrome

Signs and Symptoms

Generally, metabolic syndrome has no symptoms. Some people may have symptoms of high blood sugar (if diabetes is present) or, occasionally, of high blood pressure. Symptoms of high blood sugar often include increased thirst; increased urination, especially at night; fatigue (tiredness); and blurred vision. High blood pressure usually has no signs or symptoms. However, a few people in the early stages of high blood pressure may have dull headaches, dizzy spells, or more nosebleeds than usual.

Causes

Metabolic syndrome has several causes that act together. Some can be controlled, while others can't.

Causes that can be controlled include obesity, lack of physical activity, and insulin resistance.

Some causes that cannot be controlled by individual patients are growing older and genetics. The chance of developing metabolic syndrome increases rapidly with age. A person's genes can increase their chances of developing insulin resistance, for example, which can lead to metabolic syndrome, often even in patients with only a little extra weight around the waist.

Diagnosis

The diagnosis of metabolic syndrome is based on the results of a physical exam and blood tests. To make the diagnosis of metabolic syndrome, a physician must assess a patient and find them to have at least 3 out of 5 of the following risk factors:

• A large waistline. This indicates excess weight around the waist (abdominal obesity). A waist measurement of 35 inches or more for women and 40 inches or more for men is a component of metabolic syndrome and indicates an increased risk for heart disease and other health problems. A large waistline also is called having an "apple shape." (By contrast, a safer pattern of fat distribution is the "pear shape," common in women, in which most fat is at the hips, thighs, and buttocks.) To measure the waist, a patient stands and places a tape measure around the mid-section, just above the hipbones. He or she measures the waist just after breathing out. The tape should be snug but shouldn't squeeze the flesh.
• High triglycerides, or being on medicines specifically to treat high triglycerides. Triglycerides are a type of fat found in the blood. A triglyceride level of 150 mg/dL or higher is a component of metabolic syndrome.
• Low HDL cholesterol (high-density lipoprotein cholesterol), or being on medicine to treat low HDL. HDL is considered good cholesterol because it lowers the chances of heart disease. An HDL cholesterol level less than 50 mg/dL for women and less than 40 mg/dL for men is a component of metabolic syndrome.
• High blood pressure, or being on medicine to treat high blood pressure. A blood pressure of 130/85 or higher is a component of metabolic syndrome. If either or both of the two blood pressure numbers is high, it places a patient at risk of metabolic syndrome.
• High fasting blood sugar (glucose), or being on medicine to treat high blood sugar. A normal fasting blood sugar is less than 100 mg/dL. Fasting blood sugar between 100 and 125 mg/dL is considered prediabetes. Fasting blood sugar of 126 mg/dL or higher is considered diabetes. A fasting blood sugar of 100 mg/dL or higher (prediabetes or diabetes) is a component of metabolic syndrome.

About 85% of people who have type 2 diabetes (the most common type) also have metabolic syndrome. These people have a much higher risk for heart disease than the 15% of people who have type 2 diabetes without metabolic syndrome.

Treatment

Healthy lifestyle changes are the first line of treatment for metabolic syndrome. Lifestyle changes include weight loss, increased physical activity, an improved diet, and quitting smoking. When these lifestyle changes are implemented correctly in motivated patients, the syndrome can certainly be reversed without the need for additional intervention, particularly in people who have been recently diagnosed.

Medicines are the next line of treatment for people with very severe metabolic syndrome or people who fail to improve with lifestyle changes (or are unable/unwilling to implement them). They're used to treat and control individual risk factors such as high blood pressure, high triglycerides, low HDL cholesterol (high-density lipoprotein cholesterol), and high blood sugar. Medicines such as aspirin also may be used to reduce the risk of blood clots, a condition that often occurs with metabolic syndrome.

Medications can lower a patient's risk but should not be thought of as an alternative to a healthy diet, exercise and lifestyle. Because of the success of many of the drugs used to treat the metabolic disturbances in this syndrome, many people unfortunately believe that they do not need to make any lifestyle changes after diagnosis. This is not true. Diet and exercise are always beneficial in addition, and often can stop progression of heart disease, high blood pressure and peripheral vascular disease far more effectively than medicines alone.

Goals of treatment

The major goal of treating metabolic syndrome is to reduce a person's risk for heart disease. Treatment is directed first at reducing LDL cholesterol (low-density lipoprotein cholesterol), high blood pressure, and diabetes (if these conditions are present).

The second goal of treatment is to prevent the onset of type 2 diabetes (if it hasn't already developed). Long-term complications of diabetes often include heart and kidney disease, vision loss, and foot or leg amputation. If diabetes is present, the goal of treatment is to reduce the increased risk for heart disease by controlling all of the risk factors.

The main emphasis in the treatment of metabolic syndrome is to lessen the effects of the underlying risk factors that can be controlled, such as obesity, lack of physical activity, and an unhealthy diet.

Types of treatment

Medicines

The doctor may recommend medicines to help treat unhealthy cholesterol levels, high blood pressure, and high blood sugar. Unhealthy cholesterol levels are treated by one or more cholesterol-lowering medicines such as statins, fibrates, or nicotinic acid.

High blood pressure is treated by one or more antihypertensive medicines such as diuretics, beta blockers or angiotensin-converting enzyme (ACE) inhibitors. High blood sugar is treated with oral medicines (such as metformin), insulin injections, or both. Low-dose aspirin can help reduce the risk of forming blood clots, especially for people at high risk for heart disease.

Other types of treatment

Weight loss

In general, people with metabolic syndrome who are overweight or obese are urged to reduce their weight by 7 to 10% during the first year of treatment. For example, a person weighing 250 pounds should try to lose 18 to 25 pounds. A person weighing 300 pounds should try to lose 21 to 30 pounds. Many people struggle with weight loss because often the results are not immediate, leading to patient discouragement. Also dieting alone with "crash diets" frequently has a poor rate of success. However, weight loss is usually possible in the long term as long as it is planned in conjunction with lifestyle changes which include the adoption of regular exercise.

After the first year, people are urged to continue to lose weight to the greatest extent possible, with a long-range target of lowering their body mass index (BMI) to less than 25. BMI measures weight in relation to height and gives an estimate of total body fat. A BMI between 25 and 29.9 is considered overweight. A BMI of 30 or more is considered obese. A BMI of less than 25 is the goal for prevention and treatment of metabolic syndrome.

BMI can be calculated using the National Heart, Lung, and Blood Institute’s (NHLBI’s) online calculator, or BMI can be calculated by a health care provider.

Healthy eating plan

For a healthy eating plan, go to the NHLBI’s Aim for a Healthy Weight Web site and the NHLBI’s "Your Guide to Lowering Cholesterol With TLC." This booklet describes the Therapeutic Lifestyle Changes (TLC) diet.

With the TLC diet, less than 7% of a person's daily calories should come from saturated fat, and no more than 25 to 35% of a person's daily calories should come from all fats, including saturated, trans, monounsaturated, and polyunsaturated fats. In addition, less than 200 mg of cholesterol should be consumed per day. The amounts of fat and cholesterol in prepared foods can be found on the food's nutritional label.

Foods high in soluble fiber also are part of a healthy eating plan. These foods include:

• Whole grain cereals such as oatmeal and oat bran
• Fruits such as apples, bananas, oranges, pears, and prunes
• Legumes such as kidney beans, lentils, chick peas, black-eyed peas, and lima beans

Fish are an important part of a heart healthy diet. Fish are a good source of omega-3 fatty acids, which may help protect the heart from blood clots and inflammation and reduce the risk for heart attack.

Patients, particularly those with high blood pressure also should try to limit the amount of sodium and salt in the diet. This means choosing low-sodium and low-salt foods and “no added salt”foods and seasonings at the table or when cooking. The nutritional label on food packaging shows the amount of sodium in the item. Fresh fruit, meat and vegetables have naturally very levels of sodium and salt, whereas packaged or processed foods usually have very high levels. For patients who find low salt diets unpalatable, low sodium salt substitutes are available but should be used after consultation with a physician as many of them contain high levels of potassium.

One other important lifestyle change that is usually advised is to limit alcoholic beverages. Too much alcohol raises both blood pressure and triglyceride level. It will also add extra calories, which will cause weight gain. Men should have no more than 2 drinks containing alcohol a day. Women should have no more than one drink containing alcohol a day. Driking amounts above this level is associated with higher rates of death.

Increased physical activity

In general, people with metabolic syndrome are urged to keep up a moderate level of activity, such as brisk walking for at least 30 minutes at least 5 days of the week. This activity can be broken into shorter periods as needed—for example, three 10-minutes sessions.

The ultimate goal is for people to maintain a moderate level of physical activity 60 minutes a day for 5 days a week, but preferably daily. Many patients with metabolic syndrome find it useful to talk with a doctor about the best kind of physical activity for them before starting any kind of program, as well as to make sure they do not have any medical problems that will prevent them from exercising.

Smoking cessation

Stopping smoking is a vital part of limiting disease and disability from the conditions resulting from metabolic syndrome. Among other known harmful effects on the heart, smoking will raise the triglyceride level and lower the HDL cholesterol. People who do not or cannot stop smoking put themselves at a much higher risk of dying or becoming disabled than those who do. There are now several effective medications available to help people stop smoking who are not able to do so on their own.

Chances of Developing Metabolic Syndrome

Risk factors associated with heart disease

Having metabolic syndrome increases a patient's risk for heart disease. Heart disease risk can be divided into short-term risk (the risk for having a heart attack or dying of heart disease in the next 10 years) and long-term risk (the risk for developing heart disease over a lifetime). Even in patients who do not have metabolic syndrome, measuring the chance of developing heart disease in the next 10 years (the short-term risk) is often helpful. This depends on the number of risk factors a person has from the list above. The National Cholesterol Education Program (NCEP) has an online calculator that can be used to determine 10-year heart disease risk score. Every person with metabolic syndrome should have their 10-year-risk score calculated. Even in patients with a low risk by this index, over time metabolic syndrome will increase their chance for heart disease. This means that, regardless of the short-term risk category, metabolic syndrome should be treated (mainly with lifestyle changes) to prevent long term health problems. It should be tackled as a lifelong disorder, and great effort should be made to detect it at an early stage and prevent it from worsening. This usually requires regular physical checkups with a physician.

The five conditions listed below are metabolic risk factors for heart disease. A person can develop any one of these risk factors by itself, but they tend to occur together. Metabolic syndrome is diagnosed when a person has at least three of these risk factors:

• Abdominal obesity. Carrying a significant amount of extra fat in the abdominal area or midsection, also called "an apple shape," is a greater risk factor for heart disease than excess fat in other parts of the body, such as on the hips.
• High triglyceride level. Triglycerides are a type of fat found in the blood. A higher level than normal in the blood is associated with an increased risk for heart disease.
• Low HDL. A lower than normal level of HDL cholesterol (high-density lipoprotein cholesterol) in the blood increases the chance of heart disease. HDL is considered good cholesterol because it is associated with a lower risk of heart disease.
• High blood pressure. Blood pressure is recorded as 2 numbers, usually written one on top of or before the other, such as 120/80. The top or first number, called the systolic blood pressure, measures the pressure in the bloodstream during the heart beat. The bottom or second number, called the diastolic blood pressure, measures the pressure in the bloodstream between heartbeats when the heart is relaxed. High blood pressure is a risk for heart disease.
• High blood sugar. Higher than normal fasting blood sugar (glucose) can be an early warning sign of diabetes.

The more of these risk factors a person has, the greater the chance of developing heart disease, diabetes, or a stroke. In general, a person with metabolic syndrome is twice as likely to develop heart disease and 5 times as likely to develop diabetes as someone without metabolic syndrome.

Other risk factors

There are a number of other risk factors, in addition to those discussed above, that can increase the risk for heart disease.

• Smoking
• High LDL (low-density lipoprotein cholesterol)
• Lack of physical exercise
• Insulin resistance is a condition in which the body can't use its insulin properly. Insulin is a hormone the body uses to help change blood sugar into energy. Insulin resistance can lead to high blood sugar levels and is closely linked with being overweight or obese.
• Ethnicity
• Family history
• Older age

Related Problems

Comorbidity

Two other conditions are often found in people with metabolic syndrome, although it's not known if they cause it or worsen it. These are a tendency to form blood clots and a tendency to have a constant, low-grade inflammation throughout the body.

Other conditions that are being studied to see whether they have links to metabolic syndrome include:

• Fatty liver (excess triglycerides and other fats in the liver)
• Polycystic ovarian syndrome (a tendency to develop cysts on the ovaries)
• Gallstones
• Breathing problems during sleep such as obstructive sleep apnea
• Gout

Epidemiology

Incidence

About 47 million adults in the United States (almost 25%) have metabolic syndrome, and the numbers continue to grow. The increasing number of people with this condition is connected to the rise in obesity rates among adults. In the future, metabolic syndrome may overtake smoking as the leading risk factor for heart disease.

It is possible to prevent or delay metabolic syndrome, mainly with lifestyle changes. A healthy lifestyle is a lifelong commitment. Successfully controlling metabolic syndrome takes a long-term effort and teamwork with health care providers.

Populations affected

Among African Americans and Mexican Americans, metabolic syndrome is more common in women. It affects white women and men roughly equally.

Some racial and ethnic groups in the United States are more at risk for metabolic syndrome than others. Mexican Americans have the highest rate of metabolic syndrome (31.9%). Caucasians (23.8%) and African Americans (21.6%) have lower rates. South Asians have an increased risk for metabolic syndrome.

Other groups that are at increased risk of developing metabolic syndrome include:

• People with a sibling or parent with diabetes
• People with a personal history of diabetes
• Women with a personal history of polycystic ovary syndrome (a tendency to develop cysts on the ovaries)

Prevention

Making healthy lifestyle choices is the best way to prevent metabolic syndrome. Maintaining a healthy weight is important. Other than using a scale, there are two ways to determine that a person is at a healthy weight: waist measurement and body mass index (BMI). Waist measurements are performed as described above. BMI measures a patient's weight in relation to their height and provides an estimate of total body fat. A BMI between 25 and 29.9 is considered overweight. A BMI of 30 or more is considered obese. A BMI of less than 25 is the goal for preventing metabolic syndrome, and it is also the goal when treating metabolic syndrome. BMI can be calculated using the National Heart, Lung, and Blood Institute's online calculator, or a health care provider can calculate a patient's BMI.

To maintain a healthy weight, patients should follow a healthy eating plan and try not to overeat. This means eating fewer calories and less saturated fat, and emphasizing whole grains, fish, and fruits and vegetables. Choose unsaturated fats when eating fats and oils such as canola, olive, or sunflower oils, soft or liquid margarine, and nuts.

Increasing physical activity also can help people to maintain a healthy weight. At least 30 minutes of moderate activity (such as brisk walking) is usually advised, at least 5 days a week. With a doctor'’s permission, working up to getting 60 minutes of moderate activity 5 to 7 days a week is associated with greatly decreased risk.

Living with Metabolic Syndrome

Metabolic syndrome is a lifelong condition. However, lifestyle changes can help to reverse or reduce risk factors and reduce the occurrence of heart disease and diabetes. If a person already has heart disease and/or diabetes, lifestyle changes can help prevent or delay complications such as heart attack, stroke, and the long-term effects of diabetes. In poorly controlled diabetes, these can include blindness, severe pain from peripheral neuropathy, kidney failure leading to dialysis and limb problems including gangrene and amputation.

Making healthy lifestyle changes can include following a healthy eating plan, increasing physical activity, and quitting smoking. Part of managing metabolic syndrome also includes taking all medications as prescribed.

Clinical Trials

For a list of American government-sponsored research studies into metabolic syndrome, click here.

External Links

• Heart Attack Risk Assessment Tool
• Interactive Menu Planner
• NHLBI Online BMI Calculator
• Portion Distortion
• Your Guide to Lowering Your Cholesterol With TLC”