What Is the Impact of Excessive Iodine and Semen Quality in Fertile Men of China: An Association Study 

Abstract Background: Iodine is an essential element for hormones synthesized by the human thyroid gland. Thyroid hormone deficiency affects all body tissues, including multiple endocrine changes that alter growth hormones, corticotrophin, glucocorticoids, and gonadal function. In many countries, subfertility is an important problem affecting about 10–15% of all couples trying to conceive. Male subfertile factors have accounted for 25–30% of all cases in their studies. The aim of this study was to study the correlation between urinary iodine concentration (UIC) and semen quality of fertile male in China.Methods: semen and urine samples were collected from males who attended a survey for the reproductive physiological constants of male and female in China. All participants were fertile and they should be free from diseases of male reproductive system and thyroid related diseases. We studied the correlation between UIC and semen quality parameters in fertile males and the effect of iodine concentration on male reproduction. Participants were divided into six groups based on UIC. We measured semen parameters and UIC. Semen parameters or time-to-pregnancy (TTP) were analyzed by Spearman correlation, linear regression and multivariable logistic regression. Results: 1089 men were recruited in the study. The mean and median age of participants were 27.46±0.12 and 27±3.88 years, respectively. UIC of 274 (25.16%) men was lower than the UIC of WHO recommended. UIC of 405 men located in the region of WHO recommended. 62.35% of them were not located in the optimal region. Semen concentration and total sperm count were found to decrease when UIC increases when the UIC≥100 ug/L. Conclusions: A male with deficient UIC or excessive UIC has more risk of lower semen quality such as sperm concentration and total sperm count. In addition, if a male with deficient UIC or excessive UIC, his wife has longer TTP than the males who had normal UIC. Deficient UIC associated with lower semen quality and TTP than excessive UIC.