Peak Testosterone Forum

General Category => Testosterone, Hormones and General Men's Health => Topic started by: Anthony01234567 on August 19, 2016, 06:38:54 pm

Title: When you have blood tests done, does it really matter if you fast beforehand?
Post by: Anthony01234567 on August 19, 2016, 06:38:54 pm

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

And what exactly does "fasting" mean?

Thanks.
Title: Re: When you have blood tests done, does it really matter if you fast beforehand?
Post by: kcrunner on August 19, 2016, 06:56:33 pm
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. 
Title: Re: When you have blood tests done, does it really matter if you fast beforehand?
Post by: PeakT on August 19, 2016, 07:10:46 pm

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.
Title: Re: When you have blood tests done, does it really matter if you fast beforehand?
Post by: Osprey on August 19, 2016, 07:14:47 pm
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.
Title: Re: When you have blood tests done, does it really matter if you fast beforehand?
Post by: PeakT on August 19, 2016, 07:23:37 pm
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.
Title: Re: When you have blood tests done, does it really matter if you fast beforehand?
Post by: Osprey on August 19, 2016, 08:36:58 pm
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.
Title: Re: When you have blood tests done, does it really matter if you fast beforehand?
Post by: PeakT on August 21, 2016, 12:44:55 am
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.
Title: Re: When you have blood tests done, does it really matter if you fast beforehand?
Post by: Anthony01234567 on August 25, 2016, 08:59:06 pm
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.
Title: Re: When you have blood tests done, does it really matter if you fast beforehand?
Post by: Boxcar on August 25, 2016, 10:45:07 pm
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. 
Title: Re: When you have blood tests done, does it really matter if you fast beforehand?
Post by: PeakT on August 28, 2016, 01:17:50 pm
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