Twenty-four-hour monitoring of scrotal temperature in obese men and men with a varicocele as a mirror of spermatogenic function

Hum Reprod. 2015 May;30(5):1006-13. doi: 10.1093/humrep/dev057. Epub 2015 Mar 15.


Study question: How do day and night scrotal temperatures, spermatogenesis parameters, sex hormones and intratesticular perfusion in obese men and men with a varicocele compare with healthy controls?

Summary answer: Compared with healthy controls, 24-h monitoring of scrotal temperature in men with a varicocele and obese men showed higher temperatures and this condition was related to a significant alteration of spermatogenesis and stasis of testicular perfusion.

What is known already: Several studies have shown that increased scrotal temperature has dramatic effects on spermatogenesis. Scrotal hyperthermia by exposure to sauna is able to induce a significant alteration of sperm production.

Study design, size and duration: In a case-control study, data were collected over a period of 2 years from 60 subjects with risk factors for testicular heating and 20 healthy subjects who consecutively attended an andrology unit as participants in an infertility prevention program.

Participants/materials, setting and methods: Forty subjects with a left varicocele, 20 obese men and 20 healthy subjects who served as controls, were evaluated for testicular volumes, sex hormones, sperm parameters, sperm aneuploidies, mean transit time (MTT) of intratesticular blood and 24-h scrotal temperature monitoring by a cutaneous thermochip. Subjects with a varicocele were further subgrouped on the basis of normo or oligozoospermia (VN and VO). Student's t-test was used for statistical analysis.

Main results and the role of chance: We found a significant increase in 24-h mean scrotal temperature in obese men and men with a varicocele compared with controls (both P < 0.01). This increase in scrotal temperature was associated with impaired sperm parameters and higher FSH plasma levels compared with controls. Dynamic evaluation of scrotal temperatures showed wide fluctuations in controls, but little variation in obese men and men with a varicocele. Men with VO had left and right increase in scrotal temperatures (the right was increased also versus VN, P < 0.01) (both P < 0.001). Men with VN showed a left scrotal temperature higher than controls (P < 0.01) and a right scrotal temperature no different from controls (34.92 ± 0.53 and 34.66 ± 0.65, respectively). Mean MTT values recorded in men with VO were significantly higher than men with VN and obese men (both P < 0.001).

Limitations and reasons for caution: Different lifestyle, diet, occupation, stress level and environmental temperatures due to seasonal conditions are major limitations of this study.

Wider implications of the findings: Our data suggested for the first time that dynamic evaluation of scrotal temperatures seems to reflect alterations of testicular function and perfusion in obese men and men with a varicocele. In these clinical conditions, spermatogenic impairment and scrotal heating seem to be related to different mechanisms. The dynamic evaluation of scrotal temperature in subjects with risk factors for testicular heating could allow the identification of subjects needing treatment or a change in lifestyle.

Study funding/competing interests: No external funding was sought for this study, and the authors have no conflict of interest to declare.

Keywords: male infertility; obesity; spermatogenesis; testicular heating; varicocele.

MeSH terms

  • Adult
  • Body Mass Index
  • Body Temperature*
  • Case-Control Studies
  • Chromosomes / ultrastructure
  • Healthy Volunteers
  • Hormones / blood
  • Humans
  • Infertility, Male / diagnosis
  • Infertility, Male / physiopathology*
  • Male
  • Monitoring, Physiologic / methods
  • Obesity / complications*
  • Obesity / physiopathology*
  • Oligospermia / physiopathology
  • Risk Factors
  • Scrotum / diagnostic imaging
  • Scrotum / pathology*
  • Spermatogenesis*
  • Spermatozoa / pathology
  • Testis / physiopathology
  • Ultrasonography
  • Varicocele / diagnosis
  • Varicocele / physiopathology*


  • Hormones