OldGator
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Those with high SHBG may find this interesting:
When I started TRT 8 months ago my SHBG was 57. My doc prescribed 20mg Danazol ED (along with the TRT) to lower SHBG. While my test levels have trended up, my SHBG has been trending down over the last 8 months and I hit a new SHBG low of 27 (!) last week which prompted me to research the danazol a little more and I found this at PubMed.
PMID: 6682051 [PubMed - indexed for MEDLINE]:
Free testosterone levels during danazol therapy.Nilsson B, Södergård R, Damber MG, Damber JE, von Schoultz B.
Danazol is a testosterone (T) derivative widely used in the clinical treatment of endometriosis. Its mechanism of action is poorly understood, but is side effects are mainly androgenic. Previously it was demonstrated that danazol can displace T from sex-hormone-binding globulin (SHBG). The binding properties of danazol to SHBG and albumin were studied with the use of labeled danazol in an aqueous two-phase equilibrium partition system. Levels of total T, SHBG, and albumin were measured in 16 women undergoing danazol treatment for endometriosis. Thereafter, free and protein-bound T levels were calculated. A marked rise in free T was found during danazol therapy as compared with pretreatment levels. The data suggest that many of the effects of danazol could be explained by increased levels of free T during treatment.
Other studies I've read (which are similar) indicate the same method of action. What I don't understand, however, is this:
It seems clear that danazol competes with T for SHBG receptors, which frees up more T because the T can't bind to SHBG receptors already bound by danazol. But why does my actual level of SHBG decline?? Or is this SHBG decline related to something completely different (like the TRT itself) in which case I should be taking less danazol because there's less SHBG? (I'm confused).
When I started TRT 8 months ago my SHBG was 57. My doc prescribed 20mg Danazol ED (along with the TRT) to lower SHBG. While my test levels have trended up, my SHBG has been trending down over the last 8 months and I hit a new SHBG low of 27 (!) last week which prompted me to research the danazol a little more and I found this at PubMed.
PMID: 6682051 [PubMed - indexed for MEDLINE]:
Free testosterone levels during danazol therapy.Nilsson B, Södergård R, Damber MG, Damber JE, von Schoultz B.
Danazol is a testosterone (T) derivative widely used in the clinical treatment of endometriosis. Its mechanism of action is poorly understood, but is side effects are mainly androgenic. Previously it was demonstrated that danazol can displace T from sex-hormone-binding globulin (SHBG). The binding properties of danazol to SHBG and albumin were studied with the use of labeled danazol in an aqueous two-phase equilibrium partition system. Levels of total T, SHBG, and albumin were measured in 16 women undergoing danazol treatment for endometriosis. Thereafter, free and protein-bound T levels were calculated. A marked rise in free T was found during danazol therapy as compared with pretreatment levels. The data suggest that many of the effects of danazol could be explained by increased levels of free T during treatment.
Other studies I've read (which are similar) indicate the same method of action. What I don't understand, however, is this:
It seems clear that danazol competes with T for SHBG receptors, which frees up more T because the T can't bind to SHBG receptors already bound by danazol. But why does my actual level of SHBG decline?? Or is this SHBG decline related to something completely different (like the TRT itself) in which case I should be taking less danazol because there's less SHBG? (I'm confused).
