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Testosterone Replacement, Low T, HCG, & Beyond
Testosterone Basics & Questions
Low DHT?
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<blockquote data-quote="madman" data-source="post: 157624" data-attributes="member: 13851"><p><span style="font-size: 18px"><strong>Testosterone Metabolism</strong></span></p><p><strong><span style="color: rgb(184, 49, 47)">After testicular secretion, a small proportion of testosterone undergoes activation to two bioactive metabolites, estradiol and DHT, </span></strong>whereas the bulk of secreted testosterone undergoes inactivation by hepatic phase I and II metabolism to inactive oxidized and conjugated metabolites for urinary and/or biliary excretion (108).</p><p></p><p>[ATTACH=full]8197[/ATTACH]</p><p></p><p></p><p></p><p><strong>The amplification pathway <span style="color: rgb(184, 49, 47)">converts ~4% of circulating testosterone to the more potent, pure androgen, DHT</span> <span style="color: rgb(184, 49, 47)">(50, 52).</span></strong> DHT has higher binding affinity to (109) and 3-10 time greater molar potency in transactivation (110-112) of the androgen receptor relative to testosterone. <strong>Testosterone is converted to the most potent natural androgen DHT by the 5a-reductase enzyme that originates from two distinct genes (I and II) (113). <span style="color: rgb(26, 188, 156)">Type 1 5a-reductase is expressed in the liver, kidney, skin, and brain, </span><span style="color: rgb(44, 130, 201)">whereas type 2 5a-reductase is characteristically expressed strongly in the prostate but also at lower levels in the skin (hair follicles) and liver (113). </span></strong></p><p></p><p></p><p>As the type 2 5a-reductase enzyme results in over 95% of testosterone entering the prostate being converted to the more potent androgen DHT (121), blockade of that isoenzyme (the expression of which is largely restricted to the prostate) confines the inhibition of testosterone action to the prostate (and other urogenital sinus tissue derivatives) without blocking extra-prostatic androgen action.<strong> <span style="color: rgb(184, 49, 47)">DHT circulates at ~10% of blood testosterone concentrations, </span><span style="color: rgb(26, 188, 156)">due to spillover from the prostate (122-123) and nonprostatic sources (124). </span></strong></p><p></p><p></p><p></p><p></p><p></p><p>Keypoints:</p><p></p><p><strong>*The amplification pathway <span style="color: rgb(184, 49, 47)">converts ~4% of circulating testosterone to the more potent, pure androgen, DHT</span></strong></p><p></p><p><strong><span style="color: rgb(184, 49, 47)">*DHT circulates at ~10% of blood testosterone concentrations, </span><span style="color: rgb(26, 188, 156)">due to spillover from the prostate (122-123) and nonprostatic sources (124). </span></strong></p><p></p><p><strong>*Testosterone is converted to the most potent natural androgen DHT by the 5a-reductase enzyme that originates from two distinct genes (I and II) (113). <span style="color: rgb(26, 188, 156)">Type 1 5a-reductase is expressed in the liver, kidney, skin, and brain, </span><span style="color: rgb(184, 49, 47)">whereas type 2 5a-reductase is characteristically expressed strongly in the prostate but also at lower levels in the skin (hair follicles) and liver (113). </span></strong></p><p></p><p></p><p></p><p></p><p></p><p></p><p></p><p></p><p><span style="color: rgb(0, 0, 0)">I would also say that the concentration of type II 5a-reductase enzyme can also play a role as to why ones levels may be lower than 10%.</span></p></blockquote><p></p>
[QUOTE="madman, post: 157624, member: 13851"] [SIZE=18px][B]Testosterone Metabolism[/B][/SIZE] [B][COLOR=rgb(184, 49, 47)]After testicular secretion, a small proportion of testosterone undergoes activation to two bioactive metabolites, estradiol and DHT, [/COLOR][/B]whereas the bulk of secreted testosterone undergoes inactivation by hepatic phase I and II metabolism to inactive oxidized and conjugated metabolites for urinary and/or biliary excretion (108). [ATTACH=full]8197[/ATTACH] [B]The amplification pathway [COLOR=rgb(184, 49, 47)]converts ~4% of circulating testosterone to the more potent, pure androgen, DHT[/COLOR] [COLOR=rgb(184, 49, 47)](50, 52).[/COLOR][/B] DHT has higher binding affinity to (109) and 3-10 time greater molar potency in transactivation (110-112) of the androgen receptor relative to testosterone. [B]Testosterone is converted to the most potent natural androgen DHT by the 5a-reductase enzyme that originates from two distinct genes (I and II) (113). [COLOR=rgb(26, 188, 156)]Type 1 5a-reductase is expressed in the liver, kidney, skin, and brain, [/COLOR][COLOR=rgb(44, 130, 201)]whereas type 2 5a-reductase is characteristically expressed strongly in the prostate but also at lower levels in the skin (hair follicles) and liver (113). [/COLOR][/B] As the type 2 5a-reductase enzyme results in over 95% of testosterone entering the prostate being converted to the more potent androgen DHT (121), blockade of that isoenzyme (the expression of which is largely restricted to the prostate) confines the inhibition of testosterone action to the prostate (and other urogenital sinus tissue derivatives) without blocking extra-prostatic androgen action.[B] [COLOR=rgb(184, 49, 47)]DHT circulates at ~10% of blood testosterone concentrations, [/COLOR][COLOR=rgb(26, 188, 156)]due to spillover from the prostate (122-123) and nonprostatic sources (124). [/COLOR][/B] Keypoints: [B]*The amplification pathway [COLOR=rgb(184, 49, 47)]converts ~4% of circulating testosterone to the more potent, pure androgen, DHT[/COLOR][/B] [B][COLOR=rgb(184, 49, 47)]*DHT circulates at ~10% of blood testosterone concentrations, [/COLOR][COLOR=rgb(26, 188, 156)]due to spillover from the prostate (122-123) and nonprostatic sources (124). [/COLOR][/B] [B]*Testosterone is converted to the most potent natural androgen DHT by the 5a-reductase enzyme that originates from two distinct genes (I and II) (113). [COLOR=rgb(26, 188, 156)]Type 1 5a-reductase is expressed in the liver, kidney, skin, and brain, [/COLOR][COLOR=rgb(184, 49, 47)]whereas type 2 5a-reductase is characteristically expressed strongly in the prostate but also at lower levels in the skin (hair follicles) and liver (113). [/COLOR][/B] [COLOR=rgb(0, 0, 0)]I would also say that the concentration of type II 5a-reductase enzyme can also play a role as to why ones levels may be lower than 10%.[/COLOR] [/QUOTE]
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Testosterone Replacement, Low T, HCG, & Beyond
Testosterone Basics & Questions
Low DHT?
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