Free T Lab Ranges/Units Confusion

[bennettjc]

Hi!
This is post for fellow obsessives and professionals and everyone else. ;-)

I have heard various providers speak about desirable Free T levels being about "25-50." And it makes sense that units being attached to these ranges be in ng/dl because those are the units that Total T is reported as (in the USA anyway). Free T is supposed to be 1.5-3% of Total T, so why wouldn't the units used be the same as Total T to be user friendly?

BUT - I've gotten 3 different types of Free T tests from the 2 big labs. In each case the units are reported as pg/ml. I did a quick search and learned that to convert pg/ml you simply divide by 10. Why would the big two, LabCorp and Quest, switch the units on us?

Below I've listed the 3 tests and the reported "normal" ranges in pg/ml and ng/dl.

Also, I remember hearing somewhere that LabCorp has been reporting one of their units incorrectly and they refuse to change it! It would seem from the below that the wrong reports units would be on their Direct Free T - they report pg/ml but they really mean ng/dl as that would put their 7.2-24 in the same order of magnitude as their MS/Dialyis range and the competitor's range.

Quest Dialysis: 35.0-155.0 pg/ml (or 3.5-15.5 ng/dl)
LabCorp "Direct" (Direct analog enzyme immunoassay (EIA) ) : 7.2-24.0 pg/ml (or .72-2.4ng/dl)
LabCorp MS/Dialysis: 52-180 pg/ml (or 5.2-18ng/dl)

On a related note - on another thread "Madman" referred to the LabCorp MS/Dialysis as the gold standard. That's good to hear as I prefer my local LabCorp. But I am curious how that test was designated the best.
Thanks!
Bennett

 

[madman]

LabCorp Vs Quest free testosterone lab ranges: Why are they different?

Quest Diagnositcs' range is 35-155 pg/mL for Free Testosterone. That's 3.5-15.5 ng/dL. Labcorp's range is 9-25 ng/dL. That's a big difference. 3.5-15.5 and 9-25. My question is: If you tested at 25 ng/dL on a Labcorp test, does that mean you would've tested at 15.5 ng/dL on the Quest...

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TruTTM

Reassessing Free-Testosterone Calculation by Liquid Chromatography-Tandem Mass Spectrometry Direct Equilibrium Dialysis (2018) Assessment of FT might improve precision in the diagnosis of hyperandrogenism in women and hypogonadism in men, in particular when total T levels are borderline and in...

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Allosterically coupled multi-site binding of T to human serum albumin

Allosterically coupled multi-site binding of testosterone to human serum albumin Abhilash Jayaraj, Heidi A. Schwanz, Daniel J. Spencer, Shalender Bhasin, James A. Hamilton, B. Jayaram, Anna L. Goldman, Meenakshi Krishna, Maya Krishnan, Aashay Shah, Zhendong Jin, Eileen Krenzel, Sashi N. Nair...

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Lack of Standardization of Free Testosterone Measurement Methods and Unavailability of Harmonized Reference Ranges for Free Testosterone

Le et al. (222) surveyed 120 academic and community laboratories in the United States to characterize the distribution of assays and the associated reference values for free testosterone. In all, 84% of the surveyed laboratories sent their samples for free testosterone measurement to larger centralized reference laboratories (222). These large commercial laboratories offered a variety of methods, including ultracentrifugation, radioimmunoassay, and calculation-based algorithms, as well as equilibrium dialysis (222). Many clinical laboratories used calculated free testosterone based on published linear equations (3). The laboratories reported wide variations in the reference ranges. Only 30 of the laboratories surveyed would confirm that validation studies had been performed, and the authors advised that reference ranges provided by manufacturers and laboratories should be interpreted with caution.

In a survey of 12 academic laboratories, 12 community medical laboratories, and one national laboratory, Lazarou et al. (223) found 17 and 13 different sets of reference values for total and free testosterone, respectively, which were established largely without clinical considerations. Recently, Bhasin et al. (224) reported reference ranges for calculated free testosterone concentrations in a large, rigorously collected sample of community-dwelling men. In healthy young men of the Framingham Heart Study who were 19 to 40 years of age, the lower limit of the normal range, defined as the 2.5th percentile of calculated free testosterone, was 70 pg/mL (242.7 pmol/L) (198).



post#9

About 1 year off of T labs

So...some of you may remember some of my posts. I had struggled with TRT. Never getting dialed in. So about a year or so ago I stopped TRT. Many aspects of being off TRT for me are positive. Better sexual function...yes...TRT gives me sexual issues. Mostly large drop in cum volume and force...

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post #6/7

Very Confused - Lab Results - Advice/Insights?

I've been at this for a few years now. I've tried various methods of administration and protocols, but always seem to settle back to what has been my go to protocol of 60mg E3.5D cyp. After experimenting with a few different protocols over the past year - daily prop, daily cyp, EOD cyp, cream...

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post#9

About 1 year off of T labs

So...some of you may remember some of my posts. I had struggled with TRT. Never getting dialed in. So about a year or so ago I stopped TRT. Many aspects of being off TRT for me are positive. Better sexual function...yes...TRT gives me sexual issues. Mostly large drop in cum volume and force...

www.excelmale.com

If you are going to base your FT level on the cFTZ then 18 ng/dL would be far from low as 16.4-31.4 ng/dL would be considered a healthy range.

Some would consider 18 ng/dL sub-par as many tend to do better running higher levels 30 ng/dL.

FT level of 5-9 ng/dL would be considered low and many can suffer from low-t symptoms at levels slightly higher.

If you go by the cFTV then your FT would be considered low.




I would still look into having your FT tested using the most accurate assays Equilibrium Dialysis or Ultrafiltration.

Quest
1 Testosterone, Total and Free (NO Upper Limit) plus Hematocrit

2 Testosterone, Total, LC/MS and Free (Equilibrium Ultrafiltration)

Labcorp
3 500726: Testosterone, Free, Mass Spectrometry/Equilibrium Dialysis (Endocrine Sciences) | LabCorp (ENDOCRINE SCIENCES) reference range 5.2-28.0 ng/dL

4 070038: Testosterone, Free, Equilibrium Ultrafiltration With Total Testosterone, LC/MS-MS | LabCorp reference range 5.0-21.0 ng/dL



*Any of these will suffice but I prefer #3 that has a reference range of 5.2-28.0 ng/dL.

Most men will do well having an FT in the 20-30 ng/dL range and many will have no issues even with a FT 16 ng/dL!

 

[madman]

This is key:

When having bloodwork done it is critical that your protocol is consistent (dose T/injection frequency) and testing at the true trough as this will have a big impact on the results. (reminder for all the newbies on the forum)

Forget comparing blood work unless you are using the same lab, same assays (most accurate) TT/e2 (LC-MS/MS) and FT (Equilibrium Dialysis or Ultrafiltration).

 

[madman]

CDC STANDARDIZED TOTAL T and ESTRADIOL ASSAYS and soon to be FREE TESTOSTERONE!

How the CDC Clinical Standardization Programs Are Improving Hormone Tests - AACC.org WHAT PROGRESS HAS CDC MADE WITH STANDARDIZING TOTAL TESTOSTERONE AND ESTRADIOL TESTS? Since HoSt began in 2010, CDC has had more than 350 participants in 15 countries. Participants have shown measurable...

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[madman]

Hang in there as it is just a matter of time before this S**T SHOW comes to an end!


post# 5

Why can’t all major labs standardize and ranges?

Why can’t all major labs standardize and ranges? It’s really frustrating when you use multiple labs like Labcorp and or Quest. Isn’t there some kind of industry Association that can set the standards And methods for testing? Are use Labcorp most of the time and Quest sometimes and mayo clinic...

www.excelmale.com

 

[bennettjc]

Hang in there as it is just a matter of time before this S**T SHOIW comes to an end!


post# 5

Why can’t all major labs standardize and ranges?

Why can’t all major labs standardize and ranges? It’s really frustrating when you use multiple labs like Labcorp and or Quest. Isn’t there some kind of industry Association that can set the standards And methods for testing? Are use Labcorp most of the time and Quest sometimes and mayo clinic...

www.excelmale.com

Thanks so much for all of the info!
Nelson is correct - This is the better of the TRT forums!
Some more questions if I may:
-Why do you think both Quest and LabCorp use pg/ml for their Free Ts instead of ng/ml? It seems very user unfriendly.....
-Any thoughts as to why LabCorp continues to use incorrect units for their Free T Direct test reporting? I know many have reported this error to them. Is this just corporate arrogance?
-Why will this ****show be coming to an end?
Thanks again!
Bennett