Endocrine Abstracts

Introduction: The role of thyroid hormones is important in testicular development and function (involvement in Sertoli cell proliferation and functional maturation control and postnatally in Leydig cell differentiation and steroidogenesis). Additionally, thyroid hormone receptors are found in testicular cells throughout development and in adulthood. Our aim was to study thyroid hormone effects on testicular function.

Materials and methods: We retrospectively analyzed data from a large series of outpatients who were evaluated for couple subfertility in our andrology clinic. Men with thyroid or pituitary disorders, azoospermia or obstructive azoospermia (diagnosed by history, normal FSH levels and, in most subjects, testicular biopsy), previous surgery operation for varicocele, or receiving medications that altered testicualr or thyroid physiology were excluded. A series of 106 unselected men from the records of the clinic were included (mean age ± S.D: 34.3 ± 6.1 years, mean BMI ± S.D: 27.63 ± 4.64 kg/m²). Thirty-six subjects had total sperm count <5 × 10⁶, forty had 5–20 × 10⁶, eleven had 20–40 × 10⁶ and nineteen were normozoospermic (>40 × 10⁶). Mean ± S.D TSH levels were 1.51 ± 0.85 mIU/l; mean testosterone: 4.51 ± 1.81 ng/ml; total sperm count: 20.6 ± 28.5 × 10⁶, semen volume: 3.3 ± 1.4 ml; mean FSH: 6.1 ± 4.8 mIU/ml; mean LH: 4.3 ± 2.5 mIU/ml; mean PRL: 7.1 ± 5.1 ng/ml. Total sperm count, semen volume and testosterone levels in relation to TSH levels were evaluated using Pearson’s correlation (age and BMI were also considered as possible confounding factors).

Results: A weak correlation was found between logTSH levels and the log total sperm count with marginal statistical significance (r = + 0.16, P = 0.09). The other parameters showed no correlation with TSH.

Conclusions: We noticed a weak association between TSH levels and sperm count. With larger series maybe this relationship can be stronger. Further studies are needed to draw more reliable conclusions that would be useful in daily clinical practice.