Can Your Blood Test Lie?

One of the reasons that doctors always look at blood tests is because the blood cannot lie about the health of your body.  And just like me, you can avoid lying but not entirely tell the truth.  You can show part of the truth, but not all of the truth and people will get a completely different idea than they would if they knew all of the truth. That kind of "white lie" is exactly what the blood does.  Your blood tests are interpreted by the lab, by your physician and hopefully by you.  The truth of what the blood tests mean varies depending on the circumstances and how deeply you look into the tests you have had.  Any one test is an isolated event in time, so liver enzymes for example can go up and down virtually day to day.  So your physician may think you may have a liver problem simply because that morning you woke up naked on the beach when the last thing you remember was challenging a 300 pound guy to shots at your local watering hole last night.  Also your blood glucose can vary substantially depending on what and when you've eaten.  How many people have forgotten to fast before a blood glucose test, and didn't want to admit it to their doctor?

So to really get a good interpretation of your blood test, you need to view it not as a single event in time but as part of a history of tests over time.  That way you can see trends, variations, and anything that is very out of pattern for you.  In this way you are establishing a normal range for each blood value for you.  The "normal ranges" given by a lab are simply the average of all people tested whether they have cancer, are malnourished, are alcoholic or take megavitamins.  So normal isn't "optimal" it's simply "the norm".  You want to be optimal when you are considering your health and the most likely reason for your physician ordering blood tests for you is to confirm a diagnosis or a disease, not to judge your optimal health.  So blood testing is generally done when you are "sick" not when you're feeling your best.  These  are what establish the normal range that labs use when interpreting your individual test.  So your blood glucose is being viewed in light of all the people who lied to their doctor saying they had fasted for the test, when they actually just came from Denny's.

You also cannot view just one blood value and determine if there is cause for concern.  For instance evaluating your thyroid function takes more than just your TSH, but the TSH may be the only thing the physician looks at.  As long as that is within a "normal" range, they won't even consider additional, more illuminating tests.  But is it normal for you?  When you compare it to your previous tests, is it in the same range?

So start keeping track of your tests today.  You can even contact your physician and ask for copies of all the blood tests you've had done for the past two to three years.  Also, be sure to get a complete blood test report, not simply an interpretive letter from the doctor.  By putting your blood test results to the test, you'll get the truest possible picture of your health.