Effect of Weight on Serum T with Sub-Q TE in Men with TD

[madman]

Effect of Weight on Serum Testosterone with Subcutaneous Testosterone Enanthate in Men with Testosterone Deficiency (2020)


SAT-037

Background: In men, obesity is often associated with low testosterone (T) levels, but the information is limited as to how body weight affects the pharmacokinetic profile or dosing of testosterone therapy (TTh) in men with T deficiency. Historically, men with body mass index (BMI) >32.4 kg/m2 required higher doses of T 2% gel to achieve physiological T levels than men with BMI ≤29.1 or 29.2–32.4 kg/m2.(1) In a phase 3 trial (N=150) of subcutaneous (SC) testosterone enanthate (TE) administered weekly, concentration-guided dosing raised T levels to within physiological range in 92.7% of patients. (2) Here, we report a post hoc analysis evaluating the association between body weight and serum T levels attained with SC TE.


Methods: SC TE was evaluated in an open-label, single-arm, dose-blinded, 52-week phase 3 trial (NCT02159469). Patients self-administered 75 mg SC TE weekly during the titration phase; blinded dose adjustments in 25 mg increments occurred at pre-defined time points beyond the sixth dose. The primary endpoint of this study was the percentage of patients achieving an average serum T concentration (Cavg 0-168h) of 300 to 1,100 ng/dL at week 12. For this post hoc analysis, a linear regression model with weight and dose as independent variables was used to assess differences in mean minimum T concentration (Cmin) and Cavg 0-168h at week 12.

Results: For this analysis, 137 patients were included. Doses were 50 mg (n=25), 75 mg (n=93), and 100 mg (n=19). The mean weight was 84.4 kg, 102.2 kg, and 112.0 kg for the 50 mg, 75 mg, and 100 mg dose groups, respectively (range, 49.9–146.5 kg). The dose-normalized T Cmin was 9.2 ng/dL, 5.7 ng/dL, and 4.3 ng/dL per 1 mg of SC TE for the 50 mg, 75 mg, and 100 mg groups, respectively. The dose-normalized T Cavg 0- 168h was 12.0 ng/dL, 7.2 ng/dL, and 5.7 ng/dL per 1 mg of SC TE. In an overall linear regression model, 48.2% (P<0.0001) and 55.0% (P<0.0001) of the total variance in Cmin and Cavg 0- 168h, respectively, can be predicted from the independent weight and dose variables.

Conclusion: Our results show an inverse relationship between body weight and T exposure. Men with higher mean body weights required higher doses of SC TE to achieve physiologic T levels compared with men with lower mean body weights. The available doses provide effective options to reach target exposures. These findings highlight the impact of weight and dose selection on SC TE exposure.

 

[madman]

Variance in Peak and Trough T Levels in Men Using Intramuscular T Injections

MP85-14 VARIANCE IN PEAK AND TROUGH TESTOSTERONE LEVELS IN MEN USING INTRAMUSCULAR TESTOSTERONE Bruno Nascimento*, Helen L Bernie, Elizabeth Schofield, John P. Mulhall, New York, NY INTRODUCTION AND OBJECTIVES In men using intramuscular testosterone (IM T), clinical experience shows us that...

www.excelmale.com

 

[Cataceous]

Effect of Weight on Serum Testosterone with Subcutaneous Testosterone Enanthate in Men with Testosterone Deficiency (2020)
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@readalot previously pointed out that these results may be reflecting the inverse correlation of SHBG with body mass. If free testosterone can be viewed as fixed at a particular dose then lower SHBG implies lower total testosterone. The alternative is for body mass to be positively correlated with the metabolic clearance rate of testosterone, which seems questionable given that most of the metabolization occurs in the liver. The clearance rate of insulin, for example, shows an inverse relationship with body mass.

 

[IndyColts18to88]

So with the above studies... I'm 6'5" 280lbs and was prescribed 100mg per week... with my size, would the study above imply that i'd need a higher dose? And then that would go down as my body weight went down? I just started about a week ago, doing daily subQ (i have low SHBG...probably due to being overweight)...so definitely curious!

 

[Cataceous]

So with the above studies... I'm 6'5" 280lbs and was prescribed 100mg per week... with my size, would the study above imply that i'd need a higher dose? And then that would go down as my body weight went down? I just started about a week ago, doing daily subQ (i have low SHBG...probably due to being overweight)...so definitely curious!

Your low SHBG will make total testosterone appear relatively low. This should be disregarded, with the focus being on free testosterone. Measure free testosterone using equilibrium dialysis. As a backup you can calculate free testosterone if you monitor both total testosterone and SHBG.

You're averaging 10 mg of testosterone daily, which is at or over top-of-range for natural production. Chances are good you will see robust, or even excessive free testosterone. In actuality, 75 mg per week is a better starting dose, and is what's used in the case of the Xyosted product, which I believe is what's used in the study referenced above.

As I implied in my previous post, there's probably not much reason for higher body mass to increase testosterone requirements. If you go back to a fluid flow analogy, in which testosterone is viewed as flowing into and out of the body, then you'll note that in steady state conditions the size of the body doesn't change anything with respect to the flows. In absolute terms perhaps your body can hold twice as much testosterone as a smaller guy's, but the total amounts are small and not too relevant anyway. For a crude estimate assume that normal plasma levels reflect a body-wide average. If a 100 kg man has a testosterone concentration of 1,000 ng/dL and we just say his volume is 100 liters then the total testosterone in his body is only 1 mg. Therefore a larger guy needs to accumulate only an extra fraction of a milligram of testosterone to be at parity with a smaller, but otherwise identical man.

If being larger implied that one's liver were more efficient at metabolizing testosterone then this would suggest an increase in testosterone requirements with size. However, I haven't come across anything suggesting this, and as noted, the opposite appears to be true with insulin.

 

[IndyColts18to88]

Your low SHBG will make total testosterone appear relatively low. This should be disregarded, with the focus being on free testosterone. Measure free testosterone using equilibrium dialysis. As a backup you can calculate free testosterone if you monitor both total testosterone and SHBG.

You're averaging 10 mg of testosterone daily, which is at or over top-of-range for natural production. Chances are good you will see robust, or even excessive free testosterone. In actuality, 75 mg per week is a better starting dose, and is what's used in the case of the Xyosted product, which I believe is what's used in the study referenced above.

As I implied in my previous post, there's probably not much reason for higher body mass to increase testosterone requirements. If you go back to a fluid flow analogy, in which testosterone is viewed as flowing into and out of the body, then you'll note that in steady state conditions the size of the body doesn't change anything with respect to the flows. In absolute terms perhaps your body can hold twice as much testosterone as a smaller guy's, but the total amounts are small and not too relevant anyway. For a crude estimate assume that normal plasma levels reflect a body-wide average. If a 100 kg man has a testosterone concentration of 1,000 ng/dL and we just say his volume is 100 liters then the total testosterone in his body is only 1 mg. Therefore a larger guy needs to accumulate only an extra fraction of a milligram of testosterone to be at parity with a smaller, but otherwise identical man.

If being larger implied that one's liver were more efficient at metabolizing testosterone then this would suggest an increase in testosterone requirements with size. However, I haven't come across anything suggesting this, and as noted, the opposite appears to be true with insulin.

I'm glad to see your opinion... i'm obviously new to this, but i've been doing 77mg per week total (daily subq) and hoping for good results... i'm someone who has had issues with panic attacks in my past, so hoping that the TRT doesnt bring them back! I know with some guys it helps and others it hurts...so we shall see