Thyroid hormone: the modulator of erectile function in the rabbit

Is There a Role for Levo-Thyroxine for the Treatment of Arterial Erectile Dysfunction? The Clinical Relevance of the Mean Platelet Volume

BACKGROUND

Arterial erectile dysfunction (ED) is an early sign of vascular damage. Rare evidence has been published so far as to whether subclinical hypothyroidism (SCH) affects arterial erectile function. Therefore, the objective of this study was to fill this gap.

METHODS

Patients with arterial ED and SCH were consecutive enrolled and randomly divided into Group A (n = 20) and Group B (n = 20). Group A was treated with levo-thyroxine (LT4) at the dose of 1 µg/kg/day for six months, whereas patients of the group B did not receive any treatment. Thyroid stimulating hormone (TSH), free-thyroxine (FT4), peak systolic velocity (PSV), International Index of Erectile Function 5-item version (IIEF-5) score, mean platelet volume (MPV), and total cholesterol were evaluated at enrollment (T0) and after six months (T1). Patients without hypertension, diabetes mellitus, dyslipidemia, not on drugs, and with normal total testosterone (TT) values were included in this study.

RESULTS

Group A and B did not differ for age (61.2 ± 4.8 vs. 60.3 ± 5.6 years), body-mass index (28.7 ± 2.5 vs. 28.3 ± 2.6 Kg/m²), and serum TT levels (481.2 ± 54.0 vs. 492.1 ± 59.7 ng/dL). At T0, serum TSH levels (6.5 ± 1.2 vs. 6.0 ± 1.0 µIU/mL), FT4 (8.8 ± 0.6 vs. 8.8 ± 0.6 pmol/L), PSV (26.5 ± 1.4 vs. 25.8 ± 2.1 cm/s), IIEF-5 score (8.2 ± 1.7 vs. 9.0±1.7), and total cholesterol (167.8 ± 21.7 vs. 171.6 ± 21.3 mg/dL) did not significantly differ in patients of Group A vs. those of Group B. MPV was significantly higher in Group A than in Group B (12.3 ± 0.3 vs. 11.8±0.7 fL). At T1, Group A showed significantly lower TSH (2.26 ± 0.5 µIU/mL), MPV (9.5 ± 0.3 fL), and total cholesterol (137.8 ± 29.2 mg/dL) and significantly higher FT4 (9.3 ± 0.4 pmol/L), PSV (40.0 ± 2.6 cm/s), and IIEF-5 score (20.2 ± 3.6) compared to pre-treatment values. None of these endpoints showed significant change at T1 compared to T0 in patients of group B.

CONCLUSIONS

Lt4 therapy is associated with an improvement of the erectile function at the vascular level, a decrease in MPV and total cholesterol. LT4 therapy should be considered in patients with arterial ED and SCH.

Effect of Thyroid Hormone Derangements on Sexual Function in Men and Women

INTRODUCTION

Sexual dysfunction affects many people, with 33‒60% of women reporting sexual dysfunction and 8‒52% of men with erectile dysfunction or premature ejaculation. In an effort to determine the constellation of factors responsible for sexual dysfunction, the effect of thyroid hormone derangements has been of recent interest.

AIM

To investigate the associations between thyroid hormones and sexual dysfunction in women and men.

METHODS

Literature was reviewed to examine the effects of hypo- and hyperthyroidism on sexual function.

MAIN OUTCOME MEASURE

We present a summary of the effects of thyroid dysfunction on domains of sexual functioning.

RESULTS

Most studies demonstrate that men with hypo- and hyperthyroidism have increased rates of sexual dysfunction, including erectile dysfunction in men with hypothyroidism. However, studies vary on the strength of correlation between hormonal derangement and level of sexual dysfunction. In both men with hyper- and hypothyroidism, treating the thyroid disorder at least partially reverses sexual dysfunction. In contrast, the current literature provides no consensus on the effect of hypothyroidism, hyperthyroidism, or Hashimoto's thyroiditis on female sexual function. In studies that observed increased rates of sexual dysfunction in women with thyroid disorders, correction of the thyroid derangement resulted in resolution of some sexual dysfunction. Studies are also conflicted on whether there is a relationship between the degree of sexual dysfunction and the degree of hormone derangement in women. However, prior work has demonstrated a relationship between thyroid autoantibodies and sexual dysfunction in women.

CONCLUSION

Thyroid dysfunction is an important factor in the pathogenesis of sexual dysfunction in men and possibly women. Evidence suggests a reversibility of sexual dysfunction with correction of thyroid dysfunction, although the exact pathophysiology of thyroid-mediated sexual dysfunction remains unknown. However, current evidence supports thyroid derangements rather than autoantibodies as the causative factor in men, whereas autoantibodies appear to play a more prominent role in women. Bates JN, Kohn TP, Pastuszak AW. Effect of Thyroid Hormone Derangements on Sexual Function in Men and Women. Sex Med Rev 2020;8:217-230.