Study on the Interaction between Serum Thyrotropin and Semen Parameters in Men

Area of Science:

• Endocrinology
• Reproductive Medicine
• Men's Health

Background:

• Thyroid dysfunction is known to affect male reproductive health.
• Previous studies on thyroid function and semen parameters were limited, often focusing on pathological conditions.
• The impact of thyroid hormones within the normal physiological range on semen quality requires further investigation.

Purpose of the Study:

• To investigate the association between thyroid hormone levels, specifically thyrotropin (TSH), and semen parameters in men evaluated for couple subfertility.
• To explore these relationships using various statistical regression models.

Main Methods:

• A cross-sectional study involving 130 men undergoing evaluation for subfertility.
• Data collected included semen volume, sperm concentration, total sperm count, testosterone, and TSH levels.
• Statistical analysis employed ordinary least squares regression (OLS-R), quantile regression (QR), and segmented line regression (SR).

Main Results:

• OLS-R indicated a weak negative correlation between logTSH and semen volume (r = -0.16, p = 0.05).
• QR demonstrated that increased logTSH levels were associated with decreased mean semen volume across different quantiles (p = 0.049).
• SR revealed a biphasic relationship between sperm concentration and TSH, with a peak at TSH = 1.22 μIU/mL, suggesting an optimal TSH level within the normal range.

Conclusions:

• TSH levels are weakly associated with semen volume and exhibit a biphasic relationship with sperm concentration in men with subfertility.
• The findings suggest that TSH influences semen parameters even within the typical normal range.
• TSH accounted for a small percentage of the variation in semen volume and sperm concentration, highlighting the importance of other unstudied factors.