unexamined_whimsy
Member
- Joined
- Apr 21, 2013
- Messages
- 181
SAFarmer said:Further data on sex hormones after T3 supplementation by same authors of previous study.
This study is here, http://www.ncbi.nlm.nih.gov/pubmed/9439537
There was a 42% increase in serum levels of total testosterone (18.5 +/- 1.3 to 26.3 +/- 1.8 nmol/L, P = .005) and a 150% increase in SHBG (18.0 +/- 2.2 to 44.9 +/- 7.0 nmol/L, P = .008) following T3 treatment. Estradiol and free testosterone levels were unchanged by treatment, although free testosterone decreased from 142.8 +/- 18.4 to 137.3 +/- 19.5 pmol/L.
So it seems T3 is good for the libido too ! (and no need to worry about estrogen increases)
Free testosterone has a much higher correlation with libido than total testosterone levels. It's naive to look at just an increase in total testosterone per se, since the binding strengths for testosterone and estrogen with SHBG are quite different. The intuitive notion of T/E2 ratio breaks down when SHBG is high. Further, it's difficult to find studies that measure the actual tissue concentration of estrogen -- that can be very different to the serum levels. Most importantly, there is a 'well known' (not my words, mind you) association of gynecomastia and sexual dysfunction with hyperthyroidism. Afterall, many studies even show a clear increase in serum estradiol in hyperthyroidism.