Phthalates might interfere with testicular function by reducing testosterone and insulin-like factor 3 levels

Area of Science:

• Endocrinology
• Environmental Health
• Reproductive Biology

Background:

• Phthalates are industrial plasticizers with suspected negative impacts on testosterone biosynthesis.
• The precise mechanisms by which phthalates affect male reproductive hormones, particularly testosterone and INSL3, remain underexplored in human populations.

Purpose of the Study:

• To investigate the association between phthalate exposure and the secretion of testosterone and insulin-like factor 3 (INSL3) in adult males.
• To determine if phthalates contribute to male reproductive hormone imbalance.

Main Methods:

• A case-control study involving 176 infertile and fertile men.
• Measurement of urinary phthalate metabolites and serum reproductive hormones (FSH, LH, total testosterone, estradiol, Inhibin B, INSL3).
• Statistical analyses including non-parametric tests, trend tests, and linear regression models.

Main Results:

• Higher urinary phthalate metabolite levels (e.g., MnBP, MEHP) were observed in infertile men.
• Lower serum levels of Inhibin B, TT:LH ratio, and INSL3 were found in infertile men.
• Inverse associations were identified between specific urinary phthalate metabolites and serum testosterone, free testosterone (fT), TT:LH ratio, and INSL3.

Conclusions:

• Phthalate exposure is associated with reduced secretion of testosterone and INSL3 in adult males.
• These findings suggest phthalates may adversely affect testicular/Leydig cell function.
• Further research is needed to confirm the relationship between INSL3, phthalate exposure, and Leydig cell function.