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Author Topic: When you have blood tests done, does it really matter if you fast beforehand?  (Read 5494 times)

Anthony01234567

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When you have blood tests done, does it really matter if you fast beforehand?

And what exactly does "fasting" mean?

Thanks.

kcrunner

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It depends on the blood test.   For the most part they will typically want you to fast before a lipid panel and sometimes before a glucose test. 
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PeakT

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When you have blood tests done, does it really matter if you fast beforehand?

And what exactly does "fasting" mean?

Thanks.

They will tell you how long you need to fast - 8 or 12 hours usually.
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Osprey

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Fasting usually means no solid foods and only drinking water for 12 hours before the draw. One Doctor I had said it was OK to drink black coffee or unsweetened tea.

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PeakT

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Fasting usually means no solid foods and only drinking water for 12 hours before the draw. One Doctor I had said it was OK to drink black coffee or unsweetened tea.

Kind of interesting cuzz coffee could affect insulin/glucose pulls I would think.  But there is a push now to not make the fasting tests too hard cuzz patients don't like them and don't do them.  There is even a movement to just use non-fasting #s in some cases.
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Osprey

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Fasting usually means no solid foods and only drinking water for 12 hours before the draw. One Doctor I had said it was OK to drink black coffee or unsweetened tea.

Kind of interesting cuzz coffee could affect insulin/glucose pulls I would think.  But there is a push now to not make the fasting tests too hard cuzz patients don't like them and don't do them.  There is even a movement to just use non-fasting #s in some cases.

Yeah, he was a real old fashioned doc. Since passed away.

And yes, there has been quite a bit written on using non-fasting test results. The last 2 PCP's I've had do not specify fasting for yearly physical related blood work. I still do it anyway because that's what I'm used to.

PeakT

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Fasting usually means no solid foods and only drinking water for 12 hours before the draw. One Doctor I had said it was OK to drink black coffee or unsweetened tea.

Kind of interesting cuzz coffee could affect insulin/glucose pulls I would think.  But there is a push now to not make the fasting tests too hard cuzz patients don't like them and don't do them.  There is even a movement to just use non-fasting #s in some cases.

Yeah, he was a real old fashioned doc. Since passed away.

And yes, there has been quite a bit written on using non-fasting test results. The last 2 PCP's I've had do not specify fasting for yearly physical related blood work. I still do it anyway because that's what I'm used to.

Based on what I have read, it's less accurate, but they try to compensate by using a rolling average almost?

Yeah, I don't see how you can beat fasting lipids, glucose and insulin.
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Anthony01234567

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These are the tests that I had done.  They are listed below.

Is the presence/absence of fasting in any way significant with these specific blood tests?

Thanks.

(1.)  DHT

(2.)  FSH

(3.)  LH

(4.)  Total Testosterone

(5.)  Estradiol

(6.)  PSA

(7.)  SHBG

Thank you.

This is the reason that I ask.  The doctor had told me to fast.  I had completely forgotten about that.  When I went to the blood draw, the nurse asked "did you fast?".  I lied and said "yes", when I had not actually fasted. 

Nonetheless, the only things that I did consume in the 10-12 hours before the morning blood draw were a few sips of Orange Juice (that morning) and some drinks of Lemonade (the night before).

Does the fasting (or lack of it) in any way affect the blood tests that I listed above?

Thanks.
« Last Edit: August 25, 2016, 11:24:06 pm by Anthony01234567 »

Boxcar

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These are the tests that I had done.  They are listed below.

Is the presence/absence of fasting in any way significant with these specific blood tests?

Thanks.

(1.)  DHT

(2.)  FSH

(3.)  LH

(4.)  Total Testosterone

(5.)  Estradiol

(6.)  PSA

(7.)  SHBG

Thank you.

This is the reason that I ask.  The doctor had told me to fast.  I had completely forgotten about that.  When I went to the blood draw, the nurse asked "did you fast?".  I lied and said "yes", when I had not actually fasted. 

Nonetheless, the only things that I did consume in the 10-12 hours before the morning blood draw were a few sips of Orange Juice (that morning) and some drinks of lemonade (the night before).

Does the fasting (or lack of it) in any way affect the blood tests that I listed above?

Thanks.

I would have done the same thing.

Those tests do not require fasting.  Yes, food could influence test results, but probably not enough to matter.  If anything, I would argue for making no changes to diet, since you want the test results to reflect how you normally live your life. 
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PeakT

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I split out a discussion (and study showing) that thyroid labs should probably best be pulled  in a fasted state.  Please comment here:

http://www.peaktestosterone.com/forum/index.php?topic=10839.0
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And check out my New Peak Testosterone Program: http://www.peaktestosterone.com/peak_testosterone_program
If you are on medications or have a medical condition, always check with your doctor first before making any lifestyle changes or taking new supplements.  And low testosterone is a medical condition.

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