Do You Really Need To Fast For That Blood Work?

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Recent Blog Entries From Dr. Dave Hnida


Written by Dr. Dave Hnida, CBS4 Medical EditorIt’s a pain in the neck we’ve all had to deal with at some point — starve ourselves for 12 hours, forgo the morning coffee, then stagger to the doctor’s office and wait for our blood to be drawn.

After all, we’ve been told for decades that to get an accurate snapshot of our cholesterol and blood fat levels, we need to see what the numbers are when there is no food or beverages that could sneak into the bloodstream and trigger a false reading.

Turns out, that mini-starvation and caffeine-less fog may not be necessary.

A new study of more than 209,000 people shows little difference in cholesterol levels when you fast or decide to sneak a bite or two before testing.

Total cholesterol levels and HDL (good cholesterol) levels varied by only about 1 to 2 percent when people fasted or didn’t. And LDL levels varied anywhere from 1 to 9 percent difference.

Bottom line: maybe the agony of no food or drink isn’t really necessary to get a good ballpark idea of your blood fats. Which means, your doctor could nail you any time of the day — at any office visit — without the hassle of an extra trip on some early morning.

Now the study did not look at blood sugar levels, and I’m not so sure I’m on board with an LDL reading that might be 9 percent off (say, 10-20 points away from the real reading).

But I know there are a number of people who avoid getting tested because of the inconvenience involved — and even though this one study won’t change the way we recommend testing, it might be worth grabbing that tube of blood when you’re in the doctor’s office if you’re not going to make the effort to do it another time.

And frankly, if your middle of the day results are a little funky, we can always beg and plead for you to do it again — the old-fashioned way — early and groggy.

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