JanSz
Well-known member
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The discussion is about measurement of Bio-T using RIA (assay) and calculating it using equations developed by Vermeulen
Such as these (developed in 1999 based on 1990 knowledge level):
freeTestosteron calculator
Free & Bioavailable Testosterone calculator
----------------------------------------
These 2006 paper:
---------http://www.atypon-link.com/WDG/doi/pdf/10.1515/JLM.2006.050
told me that there is:
CalcV was reported to overestimate BAT by a factor of 1.5–2.2
---------
But that was not age specific, actually the whole paper refered to "10 healthy young men "
Now this 2007 paper says that the difference is age dependent.
and is even larger
2.28 vs 3.48
3.48/2.28=1.53
--------------------------------------------------------------
I have to get a grip at this finding.
I am 67yo, this concerns me more than any body else on this board.
How to look my Quest's lab results, they calculate the BioT.
Wonder if they adjusts for age.
After all someone 20yo may get 100 and I have to get 153 to mach it.
I need a grip, someone chime in.
Is there a way to talk to someone at Quest?
================================================
Age-Associated Discrepancy between Measured and Calculated Bioavailable Testosterone in Men -- Déchaud et al. 53 (4): 723 -- Clinical Chemistry
Henri Déchaud1,2,3,a, Anne Denuzière2, Sabina Rinaldi4, Julien Bocquet3, Hervé Lejeune5 and Michel Pugeat1,6
1 INSERM ERM 0322 Hôpital Debrousse, Lyon, France.
2 Université de Lyon, Université Lyon 1, ISPB, Lyon, France,
3 Service de Radioanalyse, Centre de Médecine Nucléaire, and6 Fédération d’Endocrinologie and Hôpital Neurologique et Cardiologique (Hospices Civils de Lyon), Bron, France.
4 International Agency for Research on Cancer, Lyon, France.
5 Département de Médecine de la Reproduction, Hôpital Edouard, Herriot, and InSERM-INRA U418, Hôpital Debrousse, Lyon, France.
aAddress correspondence to this author at: Service de Radioanalyse, Centre de Médecine Nucléaire, Hôpital Neurologique et Cardiologique, 59 boul. Pinel, Bron 69394, France. E-mail [email protected].
Background: Bioavailable testosterone (BT) concentration is considered the best marker for evaluating testicular function in men. The decrease of BT in older men is more pronounced than the decrease in total testosterone because of the parallel increase in sex hormone–binding globulin (SHBG) concentrations. Measurement of BT is therefore crucial for the diagnosis of hypoandrogenism in the aging male population.
Methods: We compared BT concentrations measured by a specific RIA after ammonium sulfate precipitation (BTmeas) with those obtained by theoretical calculations (BTcal) in plasma samples from 694 young men (14 to 49 years old) and 51 older men (50 to 81 years old). We based theoretical calculations on Vermeulen’s simplified mass equation using total testosterone and SHBG concentrations.
Results: BTcal and BTmeas correlated significantly in young (Pearson r = 0.87) and aging (r = 0.89) men, but the BTcal:BTmeas ratio differed markedly between the 2 groups (2.28 vs 3.48; P <0.001).
Conclusions: In men, there is an age-associated discrepancy between calculated and measured BT concentrations. We suggest some hypotheses for the discrepancy, but additional studies will be performed to finally elucidate this difference in results and to determine the most appropriate method for BT measurements in older men.
Such as these (developed in 1999 based on 1990 knowledge level):
freeTestosteron calculator
Free & Bioavailable Testosterone calculator
----------------------------------------
These 2006 paper:
---------http://www.atypon-link.com/WDG/doi/pdf/10.1515/JLM.2006.050
told me that there is:
CalcV was reported to overestimate BAT by a factor of 1.5–2.2
---------
But that was not age specific, actually the whole paper refered to "10 healthy young men "
Now this 2007 paper says that the difference is age dependent.
and is even larger
2.28 vs 3.48
3.48/2.28=1.53
--------------------------------------------------------------
I have to get a grip at this finding.
I am 67yo, this concerns me more than any body else on this board.
How to look my Quest's lab results, they calculate the BioT.
Wonder if they adjusts for age.
After all someone 20yo may get 100 and I have to get 153 to mach it.
I need a grip, someone chime in.
Is there a way to talk to someone at Quest?
================================================
Age-Associated Discrepancy between Measured and Calculated Bioavailable Testosterone in Men -- Déchaud et al. 53 (4): 723 -- Clinical Chemistry
Henri Déchaud1,2,3,a, Anne Denuzière2, Sabina Rinaldi4, Julien Bocquet3, Hervé Lejeune5 and Michel Pugeat1,6
1 INSERM ERM 0322 Hôpital Debrousse, Lyon, France.
2 Université de Lyon, Université Lyon 1, ISPB, Lyon, France,
3 Service de Radioanalyse, Centre de Médecine Nucléaire, and6 Fédération d’Endocrinologie and Hôpital Neurologique et Cardiologique (Hospices Civils de Lyon), Bron, France.
4 International Agency for Research on Cancer, Lyon, France.
5 Département de Médecine de la Reproduction, Hôpital Edouard, Herriot, and InSERM-INRA U418, Hôpital Debrousse, Lyon, France.
aAddress correspondence to this author at: Service de Radioanalyse, Centre de Médecine Nucléaire, Hôpital Neurologique et Cardiologique, 59 boul. Pinel, Bron 69394, France. E-mail [email protected].
Background: Bioavailable testosterone (BT) concentration is considered the best marker for evaluating testicular function in men. The decrease of BT in older men is more pronounced than the decrease in total testosterone because of the parallel increase in sex hormone–binding globulin (SHBG) concentrations. Measurement of BT is therefore crucial for the diagnosis of hypoandrogenism in the aging male population.
Methods: We compared BT concentrations measured by a specific RIA after ammonium sulfate precipitation (BTmeas) with those obtained by theoretical calculations (BTcal) in plasma samples from 694 young men (14 to 49 years old) and 51 older men (50 to 81 years old). We based theoretical calculations on Vermeulen’s simplified mass equation using total testosterone and SHBG concentrations.
Results: BTcal and BTmeas correlated significantly in young (Pearson r = 0.87) and aging (r = 0.89) men, but the BTcal:BTmeas ratio differed markedly between the 2 groups (2.28 vs 3.48; P <0.001).
Conclusions: In men, there is an age-associated discrepancy between calculated and measured BT concentrations. We suggest some hypotheses for the discrepancy, but additional studies will be performed to finally elucidate this difference in results and to determine the most appropriate method for BT measurements in older men.
