T Nation

LabCorp or Quest For E2 Testing?


I decided to conduct an experiment to see what the discrepancy would be between two different labs on my estradiol test. In the past I had seen some wild numbers between the two, but the tests were done at different intervals over time. This time I decided to have my estradiol level checked at two different labs within one hour.

My first stop was at Quest Diagnostics and my blood was drawn at 6:30 AM. I then went to LabCorp and had my blood drawn at 7:30 AM (done through Life Extension). I got my results back today. Both labs used the same scale: 0-54 pg/mL. The results:

LabCorp: estradiol 30 pg/mL
Quest: estradiol 79 pg/mL

I know this can't be right - not even close. I've been using anastrazole @ 4 drops per day for three months. I am on TRT and using Testim 5 grams daily since October 2006 after being diagnosed with hypogonadism (Total T: 135 ng/dL; Free T: 30.0 pg/mL). My T levels now are:

Total T: 1438 pg/mL
Free T : 491.8 pg/mL

Based on the way I feel I'm going with LabCorp because I don't feel like my E2 is 79. However, it does make me curious. The only side effects that are bothering me is side pain on my right side (hip/glute), minor back pain and stiffness, but I figure that is due from years of heavy training and not elevaed E2. In the past, the right side hip/glute pain has alerted me to using too high of a dosage of anastrazole. Obviously, even at 30 pg/mL, that can't be the case.

How can these two labs be this far off? Which one is more reliable? Quest or LabCorp?

Thanks in advance for any thoughts that you might have for me.


I have been wondering about this experiment too.

I use LabCorp via LEF.

If one used Quest numbers, that would probably mean that your adex dose would need to increase by a factor of 79/30 = 2.63, which does not address getting E2 from 30-->22.

Your Quest driven dose of adex would become 13 drops per day to get to E2=22pg/ml; which is completely bogus. 4 X 70/22 = 12.72

To get to E2=22pg/ml: Going with LabCorp, new adex dose = old adex dose X 30/22 = 4 drops X 1.364 = 5~6 [5.456] drops per day; which seems reasonable.

When I lowered my E2 from 28-->22 I felt a bit improvement in libido, mood and energy. Expect to feel results in 1-14 days.

Why are the results so different? Something stinks.


I think the results are bogus because with Quest you're supposed to use the "ultra sensitive" E2 test. Why that is I have no idea. Are you sure about your total T labs? That seems a little curious on your current dose of Testim. If those labs are correct you absorb like wild fire!

I think your LabCorp E2 is accurate because I don't think your E2 would be 70 using even a small dose of Adex. Adex is powerful stuff.


I wish I had Test results like that. Hell, your FREE test is higher than my total test.


When not on TRT, FT is highly variable. Recommended to test in the earlier morning.

When on injected T, TF can be quite steady with frequent injections. Time of day is not an issue.

With transdermals, there can be large swings in FT and the results are influenced by timing of the lab work after application.

Bio-T may be less variable because of the albumin bound T... but I have never read anything to that point.


My total T lab results are accurate. It's been in that range for almost two years and the lab results have been consistent fluctuating between 1400-1700. When I first started using Testim and using it the conventional way (applying to the upper arms) my total T results were in the 500's. I started experimenting with application sites and found an area and a technique for application that has worked for me.

My total Adex dosage for the week adds up to the standard 1mg protocol. After two years of experimenting with Adex I found that 4 drops per day is my "sweet spot". More than that and I have side effects.


I made several phone calls today to health care professionals that I know including my own doctor's office. They were clueless as to what happened. Like I said, this is the second time this has occurred. My "gut" tells me that Quest is the culprit. I physically don't feel like my E2 is that high. My libido is very high. I have energy, motivation, drive, mental speed and wake up every morning with wood. I am lean and have vascularity. My sex drive is getting on my wife's nerves. I just don't see how estradiol could be that high. However, my curiosity is driving me nuts.

I called Quest and told them what was going on and they were furious and said they stood by their results. Matter of fact, they told me to come down to the lab in the morning and they would do the test over again free of charge. I called Life Extension and I'm still waiting on a call back from one of their doctors. Meanwhile, they wanted me to fax over the Quest report so they could look at it.

I told them that if I go by the Quest numbers I would literally have to triple my dosage of Adex and that could be devastating with side effects if that number of 79 is inaccurate. I'm going to stay at 4 drops per day until I get the numbers back. Since I don't know what to do I'm not going to change anything.

I told the rep from Life Extension that I will be happy to renew my membership if they can prove to me that LabCorp is accurate. Again, this is the second time. I joined up mainly to use the lab. If the lab is bogus I don't see any advantages of staying in. Well, the magazine is informative, but sometimes repetitive.


Quest ran a test for a female not a male LOL
COrrect test for quest is estrodial 4021 sensitive.
Despite what some professionals say alot of guys have switched over to the sensitive one or i even tell them goto lab corp as I have never had a problem and the results are linked clincally to the system. One can also get ZRT blood spot which is 5% deviation from lab corp.
Quest is just charging companies large amounts of money for an ultrasensitve test that may be valid, but for TRT is to sensitive.


Thanks for the information. I've never heard of this kind of E2 testing. One would think they (lab techs at Quest) would look at the lab slip and see that I am a male. When I went round-and-round with the rep on the phone she didn't mention any of this to me either. I guess this also isn't saying much for my doctor in that even the second time around when I went back to Quest for the retest this morning he didn't ask for this specific form of E2 test. As I suspected, I thought Quest was the culprit. My E2 levels felt like they would be 30 - not 79. As usual, it's up the patient to figure out his own TRT protocol. After three years on this TRT "crazy train" this ordeal of getting it figured out is still going on. When does it ever end?

I'm considering going back to the standard method of applying the Testim when my total T was 549 ng/dL and my free T was 174.6 pg/mL. I felt better then, was much stronger in the gym and didn't have the side effects that I do now. I also didn't have near the blood lipid issues that I do now that my total T is 1438 ng/dL and my free T is 491.8 pg/mL. It doesn't make any sense, but when my T levels were in the mid-range it was better for me. I got no boost of any kind with T levels over 1000. Go figure....


On the lab slip sent out are specific with correct testing so this does not happen for future reference. I am still making modifications to the testing form so things will not get all screwed up. It really depends on you shbg in relation ship to your e2. Higher shbg more e2 you can tolerate with out issue. lower shbg less e2 one needs.


This seems to be suggesting that there could be a place for testing free estradiol.


Whatever the reason, there is absolutely no excuse for reporting results that are dead wrong. The result should be valid or an out of range failure.

How many E2 tests does Quest have, only the 'sensitive' and 'ultrasenstive'? Can you post links to descriptions of these tests?


The rep from Quest that deals directly with doctors wanted me to come down to the clinic for a re-test on the estradiol free of charge. I did that this past weekend. She didn't say anything to me about different estradiol tests and nothing was asked of me at the clinic that morning. I wasn't shown what the rep put in the computer as to what exactly was ordered. I am guessing it's the same estradiol test as the last one and the same result is going to be shown again so this will just be a waste of time.

One of the doctors from LEF called me this afternoon. He couldn't believe it. He wanted me to fax him the lab report from Quest which I did. He said he was going to talk to the LabCorp supervisor and then back to me. I don't think the problem is with LabCorp. All the LEF doctor could say is "Somebody is wrong". If Quest has a special test for males with the E2 test they are doing a very good job of keeping that secretive. I'm going to have to ask my doctor tomorrow if he has ever heard of it ("estradiol 4021 sensitive"). Why is it always left up to the patient to figure this stuff out? How are we supposed to know this? I'm in the transportation business (FedEx) - not the medical field!


Suggest you wait and get more info from LEF and Quest the present a better package to your doc.


Unless the blood was drawn on the same arm as application.
5 think he been misleaded by his T results because with 5 grams of androgel NO ONE GETS THAT HIGH unless the testing site was contaminated with excessive gel or by having the gel on the same arm that the blood was drawn from. Common sense tells me he get other armed drawn and that was the area that did not have exposure to the gel. This is the most logical solution.
His total test is probably about 500-600 if that on 5 grams. If he been applying it the same way for past 2 years then hes been getting contaminated results. Of course it would be lower LOL no androgel was applied to that side. When ever i see results with > 1000 on androgel its most likely continated