Understanding Your Blood Test

Get information about blood pressure, cholesterol, and blood test results.
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Cholesterol tests

Understanding Your Blood Test

We hear lots of numbers being tossed around when it comes to cardiovascular health, and without a clear understanding of what they mean, this information can be downright overwhelming. Key players include total cholesterol, LDL and HDL cholesterol, cholesterol ratio, triglycerides, homocysteine, C-reactive protein, and blood pressure.

Food for Thought

The American Heart Association (AHA) recommends that healthy people limit their dietary cholesterol to less than 300 mg per day, and that people with heart disease shoot for less than 200 mg per day. The AHA also recommends that no more than 30 percent of your day's calories come from fat, and that your saturated plus trans fat intake not exceed 10 percent of total calories. (If you have heart disease, keep that number to less than 7 percent.)

Total Cholesterol

Total cholesterol is the most common measurement of blood cholesterol, and is usually expressed in milligrams per deciliter of blood (mg/dL). Knowing your total blood cholesterol level is an important first step in determining your risk for heart disease. You should make a point of having your cholesterol measured every five years, and more often if you are a man over 45 or a woman over 55.

If your total cholesterol is less than 200 mg/dL, good news!—your heart attack risk is relatively low (unless you have other risk factors). But even if you're not at high risk, it's still smart to eat quality foods and to get plenty of physical activity.

If your total cholesterol is 200-239 mg/dL it is considered borderline-high, and if it gets to 240 mg/dL or more, then it is flat-out high. In both cases, you should take steps to lower it.

LDL Cholesterol

LDL cholesterol is another vital part of the picture, and the lower it is, the better. If you are a healthy individual, your LDL should be around 130 mg/dL or lower. If you are at high risk for heart disease, your goal is an LDL below 100 mg/dL, and if you are at very high-risk, experts now say you should aim for a level below 70 mg/dL.

Food for Thought

If your LDL cholesterol is too high, your doctor may advice you to reduce your intake of saturated fat, trans fat, and dietary cholesterol, while increasing foods rich in soluble fiber. It's also important that you exercise regularly and lose weight if you're overweight. If you still can't lower your LDL, medications are available.

You are considered to be at high risk if you have …

    Coronary heart disease (CHD) or the risk equivalent—which includes diseases of the blood vessels to the brain or extremities and diabetes.
    Two or more other risk factors.

You are at very high risk if you have …

    CHD or the risk equivalent
    Multiple risk factors or severe and poorly controlled risk factors.

Risk factors include …

  • Age (45 years or older for men; 55 years or older for women, or premature menopause)
  • High blood pressure
  • Low HDL cholesterol
  • Smoking
  • A family history of cardiovascular disease

HDL Cholesterol

HDL cholesterol is the “good” type—in fact, it's the only good kind of cholesterol. Some folks are genetically blessed with high HDL readings, a lucky inherited gene which significantly reduces their risk for heart disease. Other folks have to work at increasing their numbers. Desirable HDL cholesterol levels are 40 mg/dL or higher.

If you learn that you have low HDL cholesterol, you can help raise it by not smoking, losing weight or maintaining a healthy weight, choosing monounsaturated fats (olive oil, almonds, avocadoes), and by being physically active for at least 30–60 minutes a day.

Cholesterol Ratio

The American Heart Association recommends using the absolute numbers for total blood cholesterol and HDL cholesterol levels. To the physician, they're more useful than the cholesterol ratio when choosing an appropriate treatment protocol.

However, it's still a good idea to understand the ratio because some physicians and health professionals use the ratio of total cholesterol to HDL cholesterol in place of total blood cholesterol. The ratio is obtained by dividing HDL cholesterol into the total cholesterol. For example, if a person has a total cholesterol of 200 mg/dL and an HDL cholesterol of 50 mg/dL, the ratio would be stated as 4:1. The goal is to keep the ratio below 5:1.