Meaning and Interpretation of Medical Tests

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How many times have you gone to the doctor and had tests ordered, gotten the results back, and still aren’t sure what they mean? Sadly, this is commonplace. Most people lack medical knowledge to understand their own care well, and time-pressured doctors often don’t have the time to educate their patients about their own health. Even when you have a helpful doctor and are reasonably well-informed about your health, you might forget what your doctor said or lose your notes or get two tests confused with each other.

Trying to understand some of my own medical test results recently, I ran across a couple of websites that are really helpful for explaining hundreds of the most common medical tests, both by test name and by medical conditions related to the tests. I also found many helpful articles on understanding “optimal ranges” for certain tests that are vastly different from the “reference ranges” used by labs and doctors.

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Here are links to two of the sites with the most information on many tests:

Lab Tests Online: A public resource on clinical lab testing from the laboratory professionals who do the testing

LabCorp Test Menu

Lab Tests Online

The Lab Tests Online site is sponsored by many major medical labs and is non-commercial and education in nature. The site is probably overall easier to use and understand. Therefore, it’s a good first choice to understand why a test is being ordered and what it means.


LabCorp is one of the largest medical testing laboratories in the United States. The company’s web site has a commercial purpose, part of it is to help doctors understand what tests to order via the LabCorp system.

The LabCorp Test Menu site includes much technical information on tests such as the amount of blood needed for the test, test tube and media used, the type of processing (freezing, refrigeration, etc.), and risk categories from the tests. For most tests, it also includes a very detailed multiple page write-up on the test, how it is used, and what the results mean in the “Related Documents” section of the web page. For example, click here to save and view the detailed PDF document on the C-Reactive Protein test.

Life Extension Foundation Blood Testing Information

Listed below under “further reading”, there are also some very comprehensive articles from Life Extension Foundation on what blood tests to get on a regular basis and how to interpret them. Particularly helpful are the “optimal ranges” discussed for many of the tests covered. These often differ significantly from “reference ranges” published by labs and the two websites mentioned above.

For instance, C-Reactive Protein is today viewed as a major indicator of cardiovascular disease risk. But the reference vs. optimal ranges are very different. For CRP, the optimal range for men and women is also different.

The standard reference range is that CRP under 1.0mg/L is low risk, 1.0 to 3.0 mg/L is average risk, and more than 3.0 mg/L is high risk.

But the optimal range for men is under 0.55 mg/L is low risk and for women is under 1.5 mg/L.

As you can see, if you’re a guy with a test result of 1.4 mg/L (a very common result), your test result may be “normal” according to the reference range yet indicate elevated risk for cardiovascular disease by the optimal range.

Doctors almost always go by the reference ranges, usually meaning they will not treat a developing problem until a test goes out of range, often after many years of warnings signs that were within the “normal” ranges.

If you as a patient take a more aggressive view of using dietary supplements and exercise to keep test results in optimal ranges, such diseases may not ever develop and you’ll live a longer life as a result. For this to work, however, you both have to be able to understand the test results and what to do with them. Hence websites like the ones mentioned in this posting can be very helpful to people who want to be proactive on keeping themselves healthy.

Further Reading

A Comprehensive Guide to Preventive Blood Testing (May 2004)

The 10 Most Important Blood Test (May 2006)

Blood Testing Protocols (July 2006)

Detect Your Risk of Sudden Heart Attack and Stroke (November 2008)

Aging and Glycation: The Importance of Hemoglobin A1c Testing (April 2008)

Guarding Against the Dangers of Vitamin D Deficiency (May 2007)

VAP Cholesterol Testing:
Advanced Technology Uncovers Hidden Cardiovascular Risks (May 2007)

Why DHEA May Be the Best-Validated Anti-Aging Supplement (November 2006)

CBC (Complete Blood Count) Test Result Interpretation

These statements have not been evaluated by the Food and Drug Administration. The products mentioned on this post are not intended to diagnose, treat, cure or prevent any disease.

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