This Article Full Text Full Text (PDF) All Versions of this Article: 90/10/5717    most recent Author Manuscript (PDF) Submit a related Letter to the Editor Purchase Article View Shopping Cart Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by T’Sjoen, G. G. Articles by Kaufman, J.-M. Search for Related Content PubMed PubMed Citation Articles by T’Sjoen, G. G. Articles by Kaufman, J.-M. Pubmed/NCBI databases Compound via MeSH Substance via MeSH Hazardous Substances DB ESTRADIOL Medline Plus Health Information Seniors' Health Related Collections Neuroendocrinology and Pituitary Male Endocrinology

Comparative Assessment in Young and Elderly Men of the Gonadotropin Response to Aromatase Inhibition

Department of Endocrinology (G.G.T., H.D., P.C., J.-M.K.), Ghent University Hospital, 9000 Ghent, Belgium; Department of Public Health (D.D.B.), Ghent University, 9000 Ghent, Belgium; and Department of Internal Medicine Subdivision Endocrinology (V.A.G.), Ospedale Putignano-Noci, 70017 Bari, Italy

Address all correspondence and requests for reprints to: G. T’Sjoen, M.D., Department of Endocrinology, Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium. E-mail: guy.tsjoen{at}ugent.be.

Context: Aging in men is associated with a decline in serum testosterone (T) levels.

Objective: Our objective was to assess whether decreased T in aging might result from increased estradiol (E₂) negative feedback on gonadotropin secretion.

Design and Setting: We conducted a comparative intervention study (2004) in the Outpatient Endocrinology Clinic, Ghent University Hospital.

Participants: Participants included healthy young and elderly men (n = 10 vs. 10).

Interventions: We used placebo and letrozole (2.5 mg/d) for 28 d, separated by 2 wk washout.

Main Outcome Measures: We assessed changes in serum levels of free E₂, LH, and FSH, free T, SHBG, and gonadotropins response to an iv 2.5-µg GnRH bolus.

Results: As assessed after 28 d of treatment, letrozole lowered E₂ by 46% in the young men (P = 0.002) and 62% in the elderly men (P < 0.001). In both age groups, letrozole, but not placebo, significantly increased LH levels (339 and 323% in the young and the elderly, respectively) and T (146 and 99%, respectively) (P value of young vs. elderly was not significant). Under letrozole, peak LH response to GnRH was 152 and 52% increase from baseline in young and older men, respectively (P = 0.01).

Conclusions: Aromatase inhibition markedly increased basal LH and T levels and the LH response to GnRH in both young and elderly men. The observation of similar to greater LH responses in the young compared with the elderly does not support the hypothesis that increased restraining of LH secretion by endogenous estrogens is instrumental in age-related decline of Leydig cell function.

This article has been cited by other articles:

				B Lapauw, S Goemaere, H Zmierczak, I Van Pottelbergh, A Mahmoud, Y Taes, D De Bacquer, S Vansteelandt, and J M Kaufman The decline of serum testosterone levels in community-dwelling men over 70 years of age: descriptive data and predictors of longitudinal changes Eur. J. Endocrinol., October 1, 2008; 159(4): 459 - 468. [Abstract] [Full Text] [PDF]

				S. Loves, J. Ruinemans-Koerts, and H. de Boer Letrozole once a week normalizes serum testosterone in obesity-related male hypogonadism Eur. J. Endocrinol., May 1, 2008; 158(5): 741 - 747. [Abstract] [Full Text] [PDF]

				S. Aebi and M. Rabaglio Overview of Current Approaches to Adjuvant Endocrine Therapy ASCO Educational Book, January 1, 2008; 2008(1): 9 - 13. [Abstract] [Full Text] [PDF]

				G. Raven, F. H. de Jong, J.-M. Kaufman, and W. de Ronde In Men, Peripheral Estradiol Levels Directly Reflect the Action of Estrogens at the Hypothalamo-Pituitary Level to Inhibit Gonadotropin Secretion J. Clin. Endocrinol. Metab., September 1, 2006; 91(9): 3324 - 3328. [Abstract] [Full Text] [PDF]