Free Testosterone Reference Range Confusion? 2 different ranges??

[trtuser35]

Hello everyone,

Been reading the forums for the last few months and just wanted to say what a great forum this is. Got a lot of great information from these boards! I decided to join the community as I am very confused on free testosterone.

I’m 35, and started TRT about 3 months ago. I attend a endocrinologist for adrenal insufficiency issues. However my endo isn’t the one who prescribes my Testosterone. I go to another doctor that specializes in TRT and male vitality issues.

On my last visit to my Endo, she had a bunch of blood tests taken. Part of them were Testosterone, Free Testosterone and Estradiol.

Testosterone 796
Free Testosterone > 125 pg/ml (reference range - 3.84-34.17)
Estradiol < 19.6

So anyways, she called and said my Estradiol was zero, and that my Free Testosterone is way too high, and she recommends be discontinuing the arimidex that my other doctor has me on to correct the “issue”

So, I called my TRT doctor and left a message for him to call me back.

However while I’m waiting for a call back, I looked up his latest blood results. He uses Quest Labs for the blood tests.

My most recent Free Testosterone levels from him are 151.1 pg/mL

Now when I look at the reference range on this lab, the normal range is 35.0-155.0

Out of curiosity, I looked up my primary care doctor’s results from years ago when I was younger, and his reference range was 35-155 as well, and he used LabCorp for his blood tests.

However I have seen many websites mentioning the 3.84-34.17 pg/ml range as well.

So as you can see, I am totally confused. Both ranges seem to be using the same units, however they are both COMPLETELY different. So which one is the correct range to go by. It seems as if there are two different ranges being used.

And to top it off, I read through the Blood Analysis Reference Table sticky on here and if i'm not mistaken, it's a completely different range as well.

Any help would greatly be appreciated.

 

[Vince]

Here's the right one.
Estradiol, Sensitive LC/MS/MS range 8.0 - 35.0

 

[trtuser35]

Thanks for the reply!

I'm a little confused, does that test include the free testosterone? or Is that just the Estadiol test?

 

[MarkM]

Ranges do change over the years and most labs have different ranges. LabCorp and Quest are the two largest in the US along with many smaller diagnostic labs and they can use different values. I try to stick to the same lab for lab work but I have moved all over the country and that was difficult to do. I prefer to use LabCorp personally. Within the last year the reference ranges for Total Testosterone and Free Testosterone were lowered.

If your last blood work states "Free Testosterone > 125 pg/ml (reference range - 3.84-34.17)" that appears to be a lab error as it is not likely you could be 4 times over the lab range from any lab.

When Vince refers to "Estradiol, Sensitive LC/MS/MS range 8.0 - 35.0 pg/ml" he is referring to the proper test for Estradiol Sensitive and this range is for LabCorp only.

It is best to post a copy of the actual lab results so w can better try to assist you.

 

[Vince Carter]

Yep different labs, different results. You wouldn't think that that would be the case but it is. Remember too, a lab range is just a sample from the population that that lab is testing and is not a scientific value arrived at by Dr's.

 

[Vince Carter]

and Free T is always a math derived number and not directly measured

 

[trtuser35]

Thanks all for the replies!

So I'm assuming they have different lab measures. It's so crazy how it's such a different number, the highs being 34.18 all the way to 155.0. That sounds like such a HUGE difference. I've heard of different labs being different by a few points here and there. It's kind of scary, almost as if there is not enough knowledge on the doctor's sides in regards to TRT.

I'll upload both blood reports from both doctors once I get home for comparison! Thanks again!

 

[MarkM]

Yes, it would be much easier for those of use trying to understand our lab values if all labs used the same values, units of measure, and ranges.

 

[Vince Carter]

To really have comparability in your labs you have to really get strict about it...injections at the same time, same day, blood drawn for the same lab, and so forth. Any differences there become variables and distort the ability to compare from one draw to the next.