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Testosterone Replacement, Low T, HCG, & Beyond
Blood Test Discussion
LabCorp Vs Quest free testosterone lab ranges: Why are they different?
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<blockquote data-quote="GeorgieBoy" data-source="post: 185791" data-attributes="member: 41175"><p>Quest Diagnositcs' range is 35-155 pg/mL for Free Testosterone. That's 3.5-15.5 ng/dL.</p><p></p><p>Labcorp's range is 9-25 ng/dL.</p><p></p><p>That's a big difference. 3.5-15.5 and 9-25.</p><p></p><p>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 Diagnostics test? Or would you have also tested at 25 ng/dL on the QD test?</p><p></p><p>LabCorp and Quest Laboratories have different reference ranges for serum testosterone assays and free testosterone lab ranges. Here are the details:</p><p></p><p>- According to the Quest website, the normal testosterone reference range for men is 250-1110 ng/dL[1].</p><p>- LabCorp's range for free testosterone is 9-25 ng/dL[2].</p><p>- Quest Diagnostics' range for free testosterone is 35-155 pg/mL, which is equivalent to 3.5-15.5 ng/dL[2].</p><p>- The concentration of free testosterone is typically <2% of the total testosterone concentration, and most of the total circulating testosterone is bound to sex hormone-binding globulin (SHBG) and albumin[3].</p><p>- Routinely available assay methods used to measure total testosterone are not sensitive enough to accurately quantitate the free testosterone fraction directly. Free testosterone is estimated in some tests by a direct, analogue enzyme immunoassay (EIA) [3].</p><p>- The difference in reference ranges between LabCorp and Quest may be due to different test methods used[4].</p><p>- Testosterone, Free, Bioavailable and Total, MS is a test offered by Quest Diagnostics that is helpful in assessing testicular function in males and managing hirsutism and virilization in females[5].</p><p>- Some users on forums have reported discrepancies between LabCorp and Quest's free testosterone ranges, with Quest's range being significantly higher than LabCorp's[4][6].</p><p></p><p>Citations:</p><p>[1] <a href="https://www.regenxhealth.com/post/labcorp-vs-quest-laboratories-serum-testosterone-assays-reference-range" target="_blank">LabCorp VS Quest Laboratories Serum Testosterone Assays & Reference Ranges</a></p><p>[2] <a href="https://www.excelmale.com/forum/threads/labcorp-vs-quest-free-testosterone-lab-ranges-why-are-they-different.21670/" target="_blank">LabCorp Vs Quest free testosterone lab ranges: Why are they different?</a></p><p>[3] <a href="https://www.labcorp.com/tests/144980/testosterone-free-direct" target="_blank">144980: Testosterone, Free, Direct | Labcorp</a></p><p>[4] [MEDIA=reddit]Testosterone/comments/c68v2v[/MEDIA]</p><p>[5] <a href="https://testdirectory.questdiagnostics.com/test/test-detail/14966/testosterone-free-bioavailable-and-total-ms?cc=MASTER&p=r" target="_blank">Quest Diagnostics: Test Directory</a></p><p>[6] <a href="https://forums.t-nation.com/t/beware-of-which-testosterone-test-from-quest-labs/163196" target="_blank">Beware of Which Testosterone Test from Quest Labs</a></p></blockquote><p></p>
[QUOTE="GeorgieBoy, post: 185791, member: 41175"] 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 Diagnostics test? Or would you have also tested at 25 ng/dL on the QD test? LabCorp and Quest Laboratories have different reference ranges for serum testosterone assays and free testosterone lab ranges. Here are the details: - According to the Quest website, the normal testosterone reference range for men is 250-1110 ng/dL[1]. - LabCorp's range for free testosterone is 9-25 ng/dL[2]. - Quest Diagnostics' range for free testosterone is 35-155 pg/mL, which is equivalent to 3.5-15.5 ng/dL[2]. - The concentration of free testosterone is typically <2% of the total testosterone concentration, and most of the total circulating testosterone is bound to sex hormone-binding globulin (SHBG) and albumin[3]. - Routinely available assay methods used to measure total testosterone are not sensitive enough to accurately quantitate the free testosterone fraction directly. Free testosterone is estimated in some tests by a direct, analogue enzyme immunoassay (EIA) [3]. - The difference in reference ranges between LabCorp and Quest may be due to different test methods used[4]. - Testosterone, Free, Bioavailable and Total, MS is a test offered by Quest Diagnostics that is helpful in assessing testicular function in males and managing hirsutism and virilization in females[5]. - Some users on forums have reported discrepancies between LabCorp and Quest's free testosterone ranges, with Quest's range being significantly higher than LabCorp's[4][6]. Citations: [1] [URL="https://www.regenxhealth.com/post/labcorp-vs-quest-laboratories-serum-testosterone-assays-reference-range"]LabCorp VS Quest Laboratories Serum Testosterone Assays & Reference Ranges[/URL] [2] [URL="https://www.excelmale.com/forum/threads/labcorp-vs-quest-free-testosterone-lab-ranges-why-are-they-different.21670/"]LabCorp Vs Quest free testosterone lab ranges: Why are they different?[/URL] [3] [URL="https://www.labcorp.com/tests/144980/testosterone-free-direct"]144980: Testosterone, Free, Direct | Labcorp[/URL] [4] [MEDIA=reddit]Testosterone/comments/c68v2v[/MEDIA] [5] [URL="https://testdirectory.questdiagnostics.com/test/test-detail/14966/testosterone-free-bioavailable-and-total-ms?cc=MASTER&p=r"]Quest Diagnostics: Test Directory[/URL] [6] [URL="https://forums.t-nation.com/t/beware-of-which-testosterone-test-from-quest-labs/163196"]Beware of Which Testosterone Test from Quest Labs[/URL] [/QUOTE]
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Testosterone Replacement, Low T, HCG, & Beyond
Blood Test Discussion
LabCorp Vs Quest free testosterone lab ranges: Why are they different?
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