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Lab Results

What Do They Mean? What Can We Do?

Volume 10, Number 5 – June 2006

Editors: Carol A. Rice, Ph.D., RN, Professor and Extension Health Specialist, and Janet M. Pollard, MPH, Extension Associate-Health

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Lab Results: What do they mean? What can we do?

Did you ever go to the doctor for lab work and have no idea what they tested, why they tested, or what your results meant when you received them? Most likely, we all have had some confusion over lab reports at one time or another. Part of the solution to this confusion is good communication. It is important to ask your doctor questions before and after tests are performed. The other part of the solution is to gain a basic understanding of some of the common tests that are performed. This issue of HealthHints will give you a short course in the meaning of some of the commonly used terms and numbers in lab reports, as well as how you can make healthy changes where possible and necessary.

Terminology: Understanding what’s being tested

The lab report says…your serum glucose level returned to normal; your lipid profile indicates that your total cholesterol is high, your LDLs are high, your HDLs are low, and your triglycerides are high…and by the way, your urinalysis came back normal.

Great, now you have all the information you need…or NOT! What do these terms mean, and how can we use them to help us toward healthier living? Let’s take a look at what’s being tested.

Serum glucose/blood glucose

Serum glucose or blood glucose are terms used to describe blood sugar. Blood always has some sugar (also called glucose) in it to produce energy. Having too much blood sugar or too little can result in serious health problems. Of particular concern is diabetes.

When you look at your “blood glucose” or “serum glucose” report, you will likely see a number such as 95 (see the Mock Lab Report and What Do Your Numbers Mean? PowerPoint® presentation that is linked on page 5 for examples of what your report might look like). The number may be followed by mg/dL, which stands for milligrams of glucose (sugar) for every deciliter of blood—that is the way blood glucose is measured.

This measurement is usually taken after fasting (not eating) overnight or 12 hours before the test because dietary intake of carbohydrates highly affects your blood sugar level.1

Lipid profile/panel

The term lipid profile or lipid panel is used to describe a group of tests that are often ordered together to determine the risk of coronary heart disease. “The tests that make up a lipid profile are tests that have been shown to be good indicators of whether someone is likely to have a heart attack or stroke caused by blockage of blood vessels (hardening of the arteries).”2

The tests in the lipid profile include:

To understand what these tests cover, we must first understand what lipids, cholesterol, lipoproteins, and triglycerides are.

Lipids are fatty substances in your blood. These substances include cholesterol and triglycerides.3

Cholesterol is a soft, waxy substance found in all parts of the body. It is manufactured in the liver for normal body functions, including production of hormones, bile acid, and vitamin D. It is transported in the blood to be used by all parts of the body. Cholesterol is also found in foods such as eggs, dairy products, meats, and poultry. Foods of plant origin contain no cholesterol.4

“Cholesterol and other fats can’t dissolve in the blood. They have to be transported to and from the cells by special carriers called lipoproteins [emphasis added].”5 There are several kinds of lipoproteins, but the ones we will focus on are LDL and HDL.

LDL-cholesterol stands for low-density lipoprotein, which is often called bad or lethal cholesterol. “Low-density lipoprotein is the major cholesterol carrier in the blood. If too much LDL cholesterol circulates in the blood, it can slowly build up in the walls of the arteries feeding the heart and brain. Together with other substances it can form plaque, a thick, hard deposit that can clog those arteries. This condition is known as atherosclerosis. A clot (thrombus) that forms near this plaque can block the blood flow to part of the heart muscle and cause a heart attack. If a clot blocks the blood flow to part of the brain, a stroke results.”5

HDL-cholesterol stands for high-density lipoprotein cholesterol, which is often called good or healthy cholesterol. About 1/3 to 1/4 of blood cholesterol is carried by HDL. “Medical experts think HDL tends to carry cholesterol away from the arteries and back to the liver where it passes from the body. Some experts believe HDL removes excess cholesterol from plaques and thus slows their growth.”5 HDL cholesterol is known as ‘good’ cholesterol because a high HDL level seems to protect against heart attack, while a low HDL level indicates a greater risk.5

Triglycerides [emphasis added] are compounds used by the body to move fatty acids (formed when fats or oils are consumed) through the blood. These fatty acids may be used by the body for energy or stored (as fat) for later use.”6 “Triglyceride is the chemical term for a specific type of fat. Triglycerides are found naturally in your body and in certain foods. Your body makes triglycerides from excess calories—regardless of their source, such as fats, proteins, or sugar (carbohydrates). Elevated levels of triglycerides put you at greater risk of cardiovascular (CV) disease.”7

“When you eat a meal high in calories, your body stores some of it as blood sugar (glucose) for a quick energy source. But it converts most of it to fat (triglycerides), which your body stores as energy to use later. For this reason, foods high in sugar can elevate triglyceride levels.”7

Total cholesterol, like all measures in a lipid profile, is used as an indicator of heart disease risk. Often, when a doctor or technician refers to your cholesterol level, he/she is referring to total cholesterol, which is calculated as follows:

Note: VLDLs are considered another “bad” lipoprotein, which contains the highest amount of triglyceride. There is no simple, direct way to measure VLDLs, so VLDLs are usually calculated as a percentage of triglycerides.8 For total cholesterol, VLDLs are estimated as 1/5 of your triglyceride level, or triglycerides divided by 5.6,9 For instance, in our mock lab report, the total cholesterol level would be calculated as follows:

“In most cases, the higher your total cholesterol, the higher your risk for heart disease.”6 Cholesterol levels are typically measured in milligrams (mg) of cholesterol per deciliter (dL) of blood, denoted as mg/dL on your lab report.

Urinalysis is simply a test done on your urine. The urine can be physically and/or chemically examined.10 Urinalysis is the final item seen on our mock lab report. Although we won’t discuss urine tests in further detail in this issue of HealthHints, it is important to note that a urinalysis can detect signs of urinary tract infection, diabetes, or other internal diseases. It is often a normal part of any lab procedure.

A Look at Your Levels: Are my numbers high, low, or normal?

Now that we know a bit more about what the words mean, let’s take a look at the numbers. What’s high? What’s low? What makes me “at risk”? What makes me “normal risk”? When am I on a borderline between normal and “at risk”? (Note: You can see the What Do Your Numbers Mean? PowerPoint presentation as you review these levels with clientele.)

Fasting Blood Sugar

Fasting blood sugar levels typically help diagnose diabetes, but they may also be used to diagnose hypoglycemia (low blood sugar).

A fasting blood sugar value by itself cannot distinguish between type 1 and type 2 diabetes. Your doctor may repeat this and other tests on a different day to confirm a diagnosis.1,11

Diabetes?

If asked to describe diabetes, some will say it means you have too much sugar in the blood; others will say it means there is not enough insulin to take care of the sugar or glucose in your blood—both are true. With type 2 diabetes (about 95% of cases of diabetes are type 2), insulin is produced, but it does not work well enough to help the sugar get from your blood into your cells to give you energy. When this happens, your body’s cells begin to die, causing problems.12 For more information on diabetes, see What is Diabetes? at http://fcs.tamu.edu/health/type_2_diabetes/what_is_diabetes.php.

LDL Cholesterol

“Because LDL cholesterol has a major association with heart disease, it’s the main focus of cholesterol-lowering treatment.”13 LDL cholesterol goals depend on how many other risk factors you have. You may be at higher risk if you have had a heart attack in the past or if you have diabetes. You may also be in a higher risk group if you have two or more of the following risk factors:

Standard guidelines for LDL cholesterol are as follows:

If you are anywhere in the categories of borderline high to very high, you will want to consult your doctor immediately and start making lifestyle changes. Your doctor may recommend a cholesterol-lowering drug to help in the process.

HDL Cholesterol

Women tend to have higher HDL cholesterol than men.

Normal value ranges may vary slightly among different laboratories.16

The following guidelines generally apply to HDL cholesterol levels:

Triglycerides

“Triglyceride is the most common type of fat in the body. Many people who have heart disease or diabetes have high triglyceride levels. Normal triglyceride levels vary by age and sex. A high triglyceride level combined with low HDL cholesterol or high LDL cholesterol seems to speed up atherosclerosis (the buildup of fatty deposits in artery walls). Atherosclerosis increases the risk for heart attack and stroke.”14

Total Cholesterol

When looking at total cholesterol numbers:

 

“At a Glance: Are Your Numbers Risky”

Don’t miss the insert and PowerPoint presentation available with this issue of HealthHints to show your clientele where their optimal numbers should be for healthy cholesterol and blood sugar. Link to the mock lab report and Lab Results presentation here:

Blood Pressure: Understanding what you don’t see

One important number that you may not see on your lab report is your blood pressure. Blood pressure is especially important to understand because high blood pressure (also called hypertension) can increase your risk for disease of the arteries, heart, brain, kidneys, and eyes,17 and it can be controlled.

A nurse or technician will almost always check your blood pressure at any doctor’s appointment. You should receive your blood pressure reading then. Write your blood pressure numbers down so that you can remember them and ask questions.

Your blood pressure reading is given in the form of two numbers—usually written one over the other. The top number represents your systolic pressure (when the heart muscle contracts), while the bottom number represents your diastolic pressure (when the heart muscle relaxes).

The following are the four categories of blood pressure:

The first two categories may simply require maintaining or adopting healthy lifestyles, while the second two categories will require healthy lifestyle choices and possibly one or more medications to gain control over blood pressure.18 Consult your doctor for help in controlling your blood pressure.

When Your Levels Are Risky: What you can do

If your cholesterol or glucose numbers are not optimal, or even if they are, it is important to gain and maintain healthy levels. Eventually, we all gain some risk factors simply because we move into an older age group. Some of us are at higher risk because of family history. Still, many risk factors for heart disease, stroke, diabetes, and other serious problems can be controlled, such as blood pressure, smoking, and other lifestyle factors.

If your levels are not optimal, it is important to consult with your doctor. These guidelines should not take the place of the advice of your medical health care team.

The following section lists some ways you can work toward optimal numbers and reduced disease risk. Even if you don’t show symptoms of illness, you need to make healthy choices for prevention. High cholesterol has no symptoms. Diabetes and high blood pressure may not be detected symptomatically for years, after which irreversible damage may have already been done. Making changes now can reap benefits for years to come. Take a look at these suggestions. You may have seen many of them listed before, but maybe you don’t know why these strategies are of particular importance. We’ll try to address that here.

Make Healthy Dietary Choices

Eating more soluble fiber and less saturated fat, trans fats, cholesterol, and sodium can improve your cholesterol numbers and your blood pressure.13,19,20

Fiber

There are two types of fiber—insoluble and soluble. Insoluble fiber is an important aid in normal bowel function. Soluble fiber, however, has been shown to help lower blood cholesterol (LDLs in particular). Soluble fiber appears to reduce the absorption of cholesterol in your intestines. Gel-like soluble fiber binds bile (which contains cholesterol) and dietary cholesterol so that the body excretes it. Soluble fiber is found in foods such as oatmeal, oat bran, kidney beans, Brussels sprouts, barley, apples, strawberries, pears, prunes, and citrus fruits.21,22

Fat

The major kinds of fat we eat in our diets are saturated, polyunsaturated, monounsaturated, and trans fatty acids (also called trans fat). Saturated fat and trans fat (although unsaturated) both raise blood cholesterol.19 In fact, though you may have only heard about the negative effects of saturated fat in the past, “evidence suggests that consumption of trans fat raises LDL (“bad”) cholesterol levels and lowers HDL (“good”) cholesterol levels, causing the arteries to become clogged and increasing the risk of developing heart disease and stroke.”23

“Saturated fats are usually solid at room temperature, and they’re more stable—that is, they don’t combine readily with oxygen…The main sources of saturated fat in the typical American diet are foods from animals and some plants.”19

Trans fat is formed when liquid vegetable oils go through a chemical process called hydrogenation, in which hydrogen is added to make the oils more solid. Hydrogenated vegetable fats are used by food processors because they allow longer shelf-life and give food a desirable taste, shape, and texture.23

“The FDA estimates that the average daily intake of trans fat in the U.S. population is about 5.8 grams or 2.6 percent of calories per day for individuals 20 years of age and older.”23

Whole milk dairy products, fatty meats, partially hydrogenated vegetable oils, butter, lard, certain tropical plant oils (palm, palm kernel, coconut oils, and cocoa butter), cookies, crackers, cakes, French fries, fried onion rings, and donuts are some examples of foods containing saturated fats or trans fats.

“Polyunsaturated fats tend to help your body get rid of newly formed cholesterol. Thus, they keep the blood cholesterol level down and reduce cholesterol deposits in artery walls. Recent research has shown that monounsaturated fats may also help reduce blood cholesterol as long as the diet is very low in saturated fat. Both types of unsaturated fats may help lower your blood cholesterol level when used in place of saturated fats in your diet. But you should be moderate in eating all types of fat, because fats contain more than twice the calories of either protein or carbohydrate.”19

The American Heart Association recommends following these guidelines:

Cholesterol

“Cholesterol is vital to the structure and function of all your cells, but it’s also the main substance in fatty deposits (plaques) that can develop in your arteries. Your body makes all of the cholesterol it needs for cell function. You get additional cholesterol by eating animal foods, such as meat, poultry, seafood, eggs, dairy products, and butter.”24

The Mayo Clinic recommends limiting your intake of cholesterol to no more than 300 milligrams a day for healthy individuals.24 Individuals with risk factors may need to alter this number. Talk with your doctor about your dietary cholesterol intake.

Sodium

Consuming more sodium (salt) than you need may raise your blood pressure. Even a modest reduction in sodium intake can reduce blood pressure—bigger cutbacks mean greater reductions in blood pressure.20 “Most healthy adults need only between 1,500–2,400 milligrams (mg) of sodium a day. But if you have hypertension, are older than 50, are black, or have chronic conditions such as kidney disease or diabetes, you may be more sensitive to sodium and its ability to raise blood pressure. In that case, aim for less than 1,500 mg of sodium a day.”20 Don’t add salt to your food. A single level teaspoon of salt has 2,300 mg of sodium. You can use herbs or spices, rather than salt, to add more flavor to your foods.20 Other ways to help reduce sodium intake include reading food labels, and eating more fresh foods and fewer processed foods.20

Omega-3 Fatty Acids

With all the news about omega-3 fatty acids, we can’t leave this section without a quick discussion of their benefits. Omega-3 fatty acids are “a type of fat that helps make your blood less likely to form clots that may cause heart attacks. Omega-3s may also protect against irregular heartbeats that may cause sudden cardiac death and may decrease triglyceride levels, decrease the growth of artery-clogging plaques, lower blood pressure, and reduce the risk of stroke.”25 Some types of fish such as salmon, mackerel, and herring are known to be high in omega-3 fatty acids.25 Flaxseed is also a good source of omega-3s.26

For more information on this and other healthy diet ideas, see the following articles:

Be physically active

“Regular physical activity increases HDL cholesterol in some people. A higher HDL cholesterol is linked with a lower risk of heart disease. Physical activity can also help control weight, diabetes, and high blood pressure. Aerobic physical activity raises your heart and breathing rates. Regular moderate to intense physical activity such as brisk walking, jogging, and swimming also condition your heart and lungs.”5

Do 30 minutes or more of physical activity most days of the week. You can even do three 10–minute sessions at different times during the day.27 Choose activities that you enjoy.27

“Physical inactivity is a major risk factor for heart disease. Even moderate-intensity activities, if done daily, help reduce your risk. Examples are walking for pleasure, gardening, yard work, housework, dancing, and prescribed home exercise.”5

As with all advice, always consult your doctor first. These guidelines are not meant to replace the advice of your doctor or health care team.

For more information on physical activity, see HealthHints: Workouts that Work for You at
http://fcs.tamu.edu/health/Health_Education_Rural_Outreach/
Health_Hints/2006/jan06/workouts.php.

Lose weight or maintain a healthy weight

“Being overweight and inactive tends to increase your LDL cholesterol and lower your HDL cholesterol, exactly the opposite of what you want.”13 Excess weight can also lead to increases in blood pressure.20 “Losing just 10 pounds can reduce your blood pressure by several points. In general, the greater the weight loss, the greater the reduction in blood pressure. Weight loss also increases the effectiveness of blood pressure medications (antihypertensives).”20 Talk to your doctor to help determine your target weight and the best way to achieve it. Following the above recommendations for a healthy diet and physical activity can help with your weight-loss goals.

Avoid tobacco and secondhand smoke

Put simply, if you smoke, you must stop; if those around you smoke, help them to stop. Tobacco smoke is one of the major risk factors of heart disease that you can change or treat.5 “Smoking lowers HDL cholesterol levels and increases the tendency for blood to clot.”5 If you or someone you love smokes, what is being asked of you here can be difficult. Seek support to help in the process. Consult your doctor about possible uses of medications that may help in the process. For more information on tobacco cessation, see HealthHints: Tobacco Cessation Best Practices and Programs for Quitting Tobacco at http://fcs.tamu.edu/health/Health_Education_Rural_Outreach/
Health_Hints/2005/spring05/tobacco_cessation.php.

Use alcohol in moderation

“In some studies, moderate use of alcohol is linked with higher HDL cholesterol levels. However, because of other risks, the benefit isn’t great enough to recommend drinking alcohol if you don’t do so already.

If you drink, do so in moderation. People who consume moderate amounts of alcohol (an average of one to two drinks per day for men and one drink per day for women) have a lower risk of heart disease than nondrinkers. However, increased consumption of alcohol brings other health dangers, such as alcoholism, high blood pressure, obesity, stroke, cancer, suicide, etc. Given these and other risks, the American Heart Association cautions people against increasing their alcohol intake or starting to drink if they don’t already do so. Consult your doctor for advice on consuming alcohol in moderation.”5

Limit caffeine intake

Some studies have shown that people who drink caffeine regularly have a higher average blood pressure, while other studies suggest that individuals eventually build a tolerance to caffeine so that it doesn’t increase blood pressure. In either case, it is a good idea to check your caffeine consumption and keep it in moderation—about 200 mg per day (which is about 2 cups of coffee).20

Get routine health screenings and health care

Health screenings can help us identify problems and reduce consequences.

Consider medication options

Though we won’t discuss them at length here, there are many promising medication options. Talk with your doctor about the following possibilities:

Follow-Up: Making healthy adjustments in your life

Whatever your laboratory numbers are, be sure to follow-up with your doctor or other members of your health care team. If your doctor prescribes lifestyle changes, be sure to set a time period to see results, and come in for a follow-up appointment. Do not cancel an appointment if you haven’t met the set goals. Your doctor is there to help you reach the goals and to help you find ways that work for you.

If medication is prescribed, be sure to take it according to your doctor’s advice. If you find that you have side effects or problems in taking the medications for any reason, call your doctor’s office to make changes or adjustments rather than quitting the medication use altogether. Remember, your health care team is there to help you—that is their job. Call them when you need assistance. Be a good consumer of your own health care.


References

  1. U.S. National Library of Medicine (2006). Glucose test. Retrieved May 30, 2006. From http://
    www.nlm.nih.gov/medlineplus/ency/article/003482.htm.
  2. American Association for Clinical Chemistry (2004). Lipid profile. Retrieved June 1, 2006. From http://
    www.labtestsonline.org/understanding/analytes/lipid/glance.html.
  3. U.S. National Library of Medicine (2006). High blood cholesterol and triglycerides. Retrieved May 30,
    2006. From http://www.nlm.nih.gov/medlineplus/ency/article/000403.htm.
  4. U.S. National Library of Medicine (2006). Cholesterol. Retrieved May 30, 2006. From http://
    www.nlm.nih.gov/medlineplus/ency/article/002472.htm.
  5. American Heart Association (2006). Cholesterol. Retrieved May 28, 2006. From http://
    www.americanheart.org/presenter.jhtml?identifier=4488.
  6. U.S. National Library of Medicine (2006). Cholesterol test. Retrieved May 31, 2006. From http://
    www.nlm.nih.gov/medlineplus/ency/article/003492.htm.
  7. Mayo Clinic (2004). High triglyceride levels: How do you lower them? Retrieved June 1, 2006.
    From http://www.mayoclinic.com/health/heart-disease/AN00252.
  8. Mayo Clinic (2004). VLDL cholesterol: What is it? Retrieved May 30, 2006. From http://mayoclinic.com/
    health/vldl-cholesterol/AN01335.
  9. Genzyme Diagnostics (2006). Frequently asked questions – clinical chemistry reagents. Retrieved June
    1, 2006. From http://www.genzymediagnostics.com/products/clinicalchem/clinchem_faq.asp.
  10. U.S. National Library of Medicine (2006). Urinalysis. Retrieved May 30, 2006. From http://
    www.nlm.nih.gov/medlineplus/ency/article/003579.htm.
  11. Mayo Clinic (2004). Blood sugar tests: What’s normal? Retrieved May 28, 2006. From http://
    mayoclinic.com/health/blood-sugar/SA00102.
  12. Schoessow, C. (2006). What is diabetes? Retrieved June 1, 2006. From http://fcs.tamu.edu/health/
    type_2_diabetes/what_is_diabetes.php.
  13. Mayo Clinic (2005). Cholesterol levels: What numbers should you aim for? Retrieved May 28, 2006.
    From http://mayoclinic.com/health/cholesterol-levels/CL00001.
  14. American Heart Association (2006). Cholesterol levels. Retrieved May 28, 2006. From http://
    www.americanheart.org/presenter.jhtml?identifier=4500.
  15. U.S. National Library of Medicine (2006). LDL. Retrieved May 30, 2006. From http://
    www.nlm.nih.gov/medlineplus/ency/article/003495.htm.
  16. U.S. National Library of Medicine (2006). HDL. Retrieved May 30, 2006. From http://
    www.nlm.nih.gov/medlineplus/ency/article/003496.htm.
  17. Mayo Clinic (2005). The dangers of high blood pressure: A look at what hypertension can do to
    different parts of your body. Retrieved May 28, 2006. From http://mayoclinic.com/health/high-bloodpressure/
    HI00062.
  18. Mayo Clinic (2004). What your blood pressure measurement means. Retrieved May 28, 2006. From
    http://mayoclinic.com/health/blood-pressure/HI00043.
  19. American Heart Association (2006). Fat. Retrieved May 28, 2006. From http://www.americanheart.org/
    presenter.jhtml?identifier=4582.
  20. Mayo Clinic (2006). High blood pressure: Take steps to control it. Retrieved May 28, 2006. From http://
    mayoclinic.com/health/high-blood-pressure/HI00027.
  21. American Heart Association (2006). Cholesterol, fiber, and oat bran. Retrieved May 28, 2006. From
    http://www.americanheart.org/presenter.jhtml?identifier=4494.
  22. Mayo Clinic (2006). Cholesterol: The best foods to lower your cholesterol and protect your heart.
    Retrieved May 28, 2006. From http://mayoclinic.com/health/cholesterol/CL00002.
  23. American Heart Association (2006). Trans fat overview. Retrieved May 28, 2006. From http://
    www.americanheart.org/presenter.jhtml?identifier=4776.
  24. Mayo Clinic (2005). Healthy diet decisions: Do you know what to eat? Retrieved June 1, 2006.
    From http://www.mayoclinic.com/health/healthy-diet/NU00200.
  25. Mayo Clinic (2004). Fish FAQ: The merits and hazards of eating fish. Retrieved May 28, 2006. From
    http://mayoclinic.com/health/food-and-nutrition/NU00292.
  26. Mayo Clinic (2006). Flaxseed: Is ground or whole better? Retrieved May 28, 2006. From http://
    mayoclinic.com/health/flaxseed/AN01258.
  27. National Heart, Lung, and Blood Institute (1997). Empower yourself! Learn your cholesterol number.
    Retrieved May 31, 2006. From http://www.nhlbi.nih.gov/health/public/heart/other/chdblack/empower.pdf.

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