New Study: Letrozole once a week normalizes serum testosterone in obesity-related mal

[Random987]

DOI: 10.1530/EJE-07-0663
European Journal of Endocrinology, Vol 158, Issue 5, 741-747
Copyright © 2008 by Society of the European Journal of Endocrinology

CLINICAL STUDIES
Letrozole once a week normalizes serum testosterone in obesity-related male hypogonadism
Sandra Loves1, Janneke Ruinemans-Koerts2 and Hans de Boer1

Departments of1 , Internal Medicine2 Clinical Chemistry, Ziekenhuis Rijnstate, Wagnerlaan 55, 6800 TA Arnhem, The Netherlands

(Correspondence should be addressed to H de Boer; Email: [email protected])

Objective: Isolated hypogonadotropic hypogonadism (IHH) is frequently observed in severely obese men, probably as a result of increased estradiol (E2) production and E2-mediated negative feedback on pituitary LH secretion. Aromatase inhibitors can reverse this process. This study evaluates whether letrozole once a week can normalize serum testosterone in severely obese men and maintain its long term effect.

Design: Open, uncontrolled 6-month pilot study in 12 severely obese men (body mass index>35.0 kg/m2) with obesity-related IHH and free testosterone levels <225 pmol/l, treated with 2.5 mg letrozole once a week for 6 months.

Results: Six weeks of treatment reduced total E2 from 123±11 to 58±7 pmol/l (P<0.001, mean±S.E.M.), and increased serum LH from 4.4±0.6 to 11.1±1.5 U/l (P<0.001). Total testosterone rose from 5.9±0.5 to 19.6±1.4 nmol/l (P<0.001), and free testosterone from 163±13 to 604±50 pmol/l (P<0.001). Total testosterone rose to within the normal range in all subjects, whereas free testosterone rose to supraphysiological levels in 7 out of 12 men. The testosterone and E2 levels were stable throughout the week and during the 6-month treatment period.

Conclusion: Letrozole 2.5 mg once a week produced a sustained normalization of serum total testosterone in obese men with IHH. However, free testosterone frequently rose to supraphysiological levels. Therefore, a starting dose <2.5 mg once a week is recommended.

 

[skull]

Hmm, wonder what those supraphysiological levels might be?

 

[Jeff]

Has anybody found a good comparison chart or writeup on the different AI's that are on the market with respect to how they compare with each other? I am just wondering if these results are specific to letro, or if you can get the same affect with 6oxo, formestane, aromasin, etc.

 

[colkurtz_spf]

Hmm, wonder what those supraphysiological levels might be?

Beyond the normal range. I love your avatar. I remember seeing it on the VPX board years ago - wish I remembered the poster's name.

 

[skull]

well, I know the write up for dex says it can be used for HRT and letro takes along time to kick in, but there was some other reason why I never tried it --gonna go check out the write up

 

[neoborn]

interesting

 

[skull]

It puts your cholesterol levels in the craper like no other

 

[Mr.50]

It puts your cholesterol levels in the craper like no other

I wonder if this is still accurate when we are talking about a single does of 2.5 per week? rather then multiple times per week dosing like many do with AI's especially while on.

Mr.50

 

[skull]

I wonder if this is still accurate when we are talking about a single does of 2.5 per week? rather then multiple times per week dosing like many do with AI's especially while on.

Mr.50

If you end up testing that theory I would be very intrested to see bloodwork results-I guess you would take 2.5 every day for 60 day [for it to kick in] then once a week after that--I would try myself but Im in the middle of somthing else at the moment

 

[Mr.50]

If you end up testing that theory I would be very intrested to see bloodwork results-I guess you would take 2.5 every day for 60 day [for it to kick in] then once a week after that--I would try myself but Im in the middle of somthing else at the moment

Hey Skull I might give it a shot but I was wondering what is the mechanism that delays Letroz effects so that you would have to take it for 60 days first? I have never heard of that?

Mr.50

 

[BodyWizard]

I suspect it's a see/feel thing that has nothing to do with whether or not anything's happening, derived from the mistaken notion that hormones don't actually affect your body until the quantity /frequency / duration reaches the mythical "kick-in" point.

 

[skull]

How good is this compared with Aromasin and Arimidex, it´s too other main rivals? Well, In non-cellular systems, Letrozole (Femara) is 2-5 times more potent than anastrozole and exemestane in its inhibition of the aromatase enzyme and activity, and in cellular systems it is 10-20x more potent! It also lasts quite a long time in your body,but takes awhile to get going& Letrozole (Femara) has a whopping 2-4 day (!) ½ life, and you need to take Letrozole (Femara) for 60 days to get a steady blood plasma level (8).

part of the write up-- FROM STERIODS.COM

 

[Mr.50]

How good is this compared with Aromasin and Arimidex, it´s too other main rivals? Well, In non-cellular systems, Letrozole (Femara) is 2-5 times more potent than anastrozole and exemestane in its inhibition of the aromatase enzyme and activity, and in cellular systems it is 10-20x more potent! It also lasts quite a long time in your body,but takes awhile to get going& Letrozole (Femara) has a whopping 2-4 day (!) ½ life, and you need to take Letrozole (Femara) for 60 days to get a steady blood plasma level (8).

part of the write up-- FROM STERIODS.COM

Wow that seems really weird that for something with such a long half life you would need to take it for so long to build up a steady blood level unless the absorbtion is so poor......

 

[bioman]

Doesn't matter as it is quite powerful. Evidently powerful enough to hammer down the E2 levels in the severely obese and jack their test levels. So basically, 2-4 hours is enough to bind to a significant amount of aromatase.

 

[skull]

Doesn't matter as it is quite powerful. Evidently powerful enough to hammer down the E2 levels in the severely obese and jack their test levels. So basically, 2-4 hours is enough to bind to a significant amount of aromatase.

Where did you get the 2-4 hr info?

 

[Hyde12]

well, I know the write up for dex says it can be used for HRT and letro takes along time to kick in, but there was some other reason why I never tried it --gonna go check out the write up

Most say that Letro will destroy sex drive. Arimidex seems more user friendly.

 

[jinxie]

I wonder if this is still accurate when we are talking about a single does of 2.5 per week? rather then multiple times per week dosing like many do with AI's especially while on.

Mr.50

Yep -- enough to screw your lipid profile. There are several articles on the net comparing the AIs. I dont have them saved. But a search can locate them in 15 minutes. I know Good Guys has one.