title: Exogenous testosterone: a preventable cause of male infertility.
abstract: OBJECTIVE
  Testosterone replacement therapy inhibits spermatogenesis, representing a problem for hypogonadal men of reproductive age.
  
  
  METHODS
  A literature review of PubMed from 1990-2013. Semen analysis and pregnancy outcomes, time to recovery of spermatogenesis, serum and intratesticular testosterone levels were examined.
  
  
  RESULTS
  Exogenous testosterone suppresses intratesticular testosterone production, which is an absolute prerequisite for normal spermatogenesis. Therapies that protect the testis involve human chorionic gonadotropin (hCG) therapy or selective estrogen receptor modulators (SERMs), but may also include low dose hCG with exogenous testosterone. SERMs, such as clomiphene citrate, are effective for maintaining testosterone production and represent a well-tolerated, oral therapy. Routine use of aromatase inhibitors is not recommended based on a lack of long-term data.
  
  
  CONCLUSIONS
  Exogenous testosterone supplementation decreases sperm production. Studies of hormonal contraception indicate that most men have a return of normal sperm production within 1 year after discontinuation. Clomiphene citrate is a safe and effective therapy for men who desire to maintain future potential fertility. Although less frequently used in the general population, hCG therapy with or without testosterone supplementation represents an alternative treatment.
authors.affiliation: 1 University of Tennessee Graduate School of Medicine, Knoxville, TN, USA ; 2 University of Toronto, Toronto, CA, Canada ; 3 University of Michigan, Ann Arbor, MI, USA.
authors.forename: Lindsey E
authors.initials: LE
authors.lastname: Crosnoe
authors.affiliation: 1 University of Tennessee Graduate School of Medicine, Knoxville, TN, USA ; 2 University of Toronto, Toronto, CA, Canada ; 3 University of Michigan, Ann Arbor, MI, USA.
authors.forename: Ethan
authors.initials: E
authors.lastname: Grober
authors.affiliation: 1 University of Tennessee Graduate School of Medicine, Knoxville, TN, USA ; 2 University of Toronto, Toronto, CA, Canada ; 3 University of Michigan, Ann Arbor, MI, USA.
authors.forename: Dana
authors.initials: D
authors.lastname: Ohl
authors.affiliation: 1 University of Tennessee Graduate School of Medicine, Knoxville, TN, USA ; 2 University of Toronto, Toronto, CA, Canada ; 3 University of Michigan, Ann Arbor, MI, USA.
authors.forename: Edward D
authors.initials: ED
authors.lastname: Kim
keywords: Hypogonadism; male fertility; selective estrogen receptor modulator; spermatogenesis; testosterone
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