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

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