Letrozole once a week normalizes serum testosterone in obesity-related male hypogonadism.

@article{citeulike:2951635, abstract = {OBJECTIVE: Isolated hypogonadotropic hypogonadism (IHH) is frequently observed in severely obese men, probably as a result of increased estradiol (E(2)) production and E(2)-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/m(2)) 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 E(2) 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 E(2) 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.}, address = {Department of Internal Medicine, Ziekenhuis Rijnstate, Wagnerlaan 55, 6800 TA Arnhem, The Netherlands.}, author = {Loves, S. and Ruinemans-Koerts, J. and de Boer, H. }, citeulike-article-id = {2951635}, doi = {http://dx.doi.org/10.1530/EJE-07-0663}, issn = {1479-683X}, journal = {European journal of endocrinology / European Federation of Endocrine Societies}, keywords = {aromatase, human, letrozole, male, testosterone}, month = {May}, number = {5}, pages = {741--747}, posted-at = {2008-07-02 10:28:30}, priority = {2}, title = {Letrozole once a week normalizes serum testosterone in obesity-related male hypogonadism.}, url = {http://dx.doi.org/10.1530/EJE-07-0663}, volume = {158}, year = {2008} }

TY - JOUR ID - citeulike:2951635 L3 - citeulike-article-id:2951635 TI - Letrozole once a week normalizes serum testosterone in obesity-related male hypogonadism. JF - European journal of endocrinology / European Federation of Endocrine Societies VL - 158 IS - 5 SP - 741 EP - 747 AD - Department of Internal Medicine, Ziekenhuis Rijnstate, Wagnerlaan 55, 6800 TA Arnhem, The Netherlands. SN - 1479-683X N2 - OBJECTIVE: Isolated hypogonadotropic hypogonadism (IHH) is frequently observed in severely obese men, probably as a result of increased estradiol (E(2)) production and E(2)-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/m(2)) 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 E(2) 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 E(2) 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. KW - aromatase KW - human KW - letrozole KW - male KW - testosterone AU - Loves, S AU - Ruinemans-Koerts, J AU - de Boer, H PY - 2008/05// UR - http://dx.doi.org/10.1530/EJE-07-0663 ER -