Thyroid Hormones and Spermatozoa: In Vitro Effects on Sperm Mitochondria, Viability and DNA Integrity

You should have regular blood tests throughout your pregnancy so that your dose can be adjusted if necessary.

Leydig cells

• They are the crucial players in the regulation of male gonadal developments and reproductive functions.
• Fortunately, hypothyroidism is very rare in males with an occurrence rate of only 0.1% in the general population (21).
• It is, therefore, important to distinguish these clinical manifestations to apply an adequate treatment.

This review summarizes the normal thyroid hormone regulation of semen quality, provides an update on human and animal studies on thyroid disorders and altered semen quality and also elucidates the possible mechanism of hypothyroidism and hyperthyroidism-induced alterations in semen quality. This review also intends to highlight the necessity of large-scale cohort studies using human subjects, as the available reports used only limited number of subjects, which confines to obtain a valid conclusion. Animal studies are also required to find out the proper molecular events occur during thyroidal disorders leading to altered semen quality. Untreated hyperthyroidism can also lead to complications of high blood pressure in pregnancy, poor growth of the baby and premature delivery.

• Hypothyroidism may result in a decrease in the sex hormone binding globulin (SHBG) levels and a decrease in total serum testosterone levels, as well as a decrease in the LH and the follicle stimulating hormone (FSH) levels (21).
• Ongoing research will likely focus on how specific thyroid-related interventions improve sperm production, and whether routine thyroid function tests should be included in the diagnostic workup for male infertility.
• If the levels of antibodies are high it is likely that you and your baby will be monitored more closely.
• In prospective controlled study Krassas et al. investigated the effects of hypothyroidism on male spermatogenesis.
• Studies assessing the role of hypo- and hyperthyroidism in male infertility have also been conducted in human subjects.

In these patients, hypothyroidism was induced by stopping or by decreasing the dose of T4 over at least one synthroid precautions spermatogenic cycle. It is observed that there was a decrease in seminal volume, and progressive forward motility compared to the controls. During euthyroid state, induction of hypothyroidism did not lead to seminal changes as compared with the same patients.52Therefore, it appears, short-term post-pubertal hypothyroidism does not cause sufficient seminal alterations to impair male fertility. Jaya Kumar et al. investigated the reproductive and endocrine functions of eight male patients with primary hypothyroidism. They conducted the investigation during the hypothyroid state and after the euthyroid state was achieved with T4 substitution therapy.

Premature Ejaculation and Hyperthyroidism

• Only one recent study has focused on fertility in men with subclinical thyroid dysfunction,16 but the small number of patients investigated prevents from drawing firmconclusions.
• It could be attributed to persistent mild hyperprolactinemia as reported in the hypothyroid patients or it could be due to a rise in estrogen to testosterone ratio as reported by us and other or due to a CNS effect.
• If you stopped taking antithyroid drugs during your pregnancy you should see your doctor if you notice any symptoms of hyperthyroidism.
• If you are prescribed supplements containing iron, calcium or Gaviscon you should take these several hours before or after the levothyroxine since these can alter the absorption of levothyroxine.

In our studies, we too report a similar positive feedback effect of raised estradiol levels on LH secretion; suggesting a key role of estrogen in regulating serum gonadotropin levels. The rise in LH was not as high as seen in cycling females which could result due to high testosterone levels Figure 3.66 Boucekkine and Semrouni (1990)69 examined the effect of estradiol on basal and GnRH – stimulated gonadotropin secretion in patients with Klinefelter’s syndrome. Injections of estradiol to these patients for five days, induced an initial decline in the serum revels of FSH and LH, followed by a 6.6-fold rise in estradiol levels on day three and 1.7- fold increase in LH levels on day four of the injection. Their results also demonstrated the establishment of a positive feedback of estradiol on LH secretion in patients with Klinefelter’s syndrome. If it is untreated you may have lighter, irregular periods and find it difficult to conceive.

Sexual dysfunction affects a large portion of the male and female population and has an incompletely defined etiology. In this review we explore the impact of thyroid dysfunction on female and male sexual function. We discuss the impact of correcting thyroid derangements and the pathophysiologic basis of thyroid hormone on the genitalia, and suggest future directions for research into the impact of thyroid disease on sexual functioning. The good news for men facing thyroid dysfunction is that thyroid-related fertility issues are often reversible with proper treatment. Men with hypothyroidism may benefit from hormone replacement therapy to regulate thyroid levels and restore normal semen quality. Those with hyperthyroidism can undergo treatments like antithyroid medications, radioactive iodine therapy, or surgery to control excess hormone production, resulting in improved semen analysis outcomes and fertility potential.

Studies assessing the role of hypo- and hyperthyroidism in male infertility have also been conducted in human subjects. Hypothyroidism may result in a decrease in the sex hormone binding globulin (SHBG) levels and a decrease in total serum testosterone levels, as well as a decrease in the LH and the follicle stimulating hormone (FSH) levels (21). In cases of prolonged pre-pubertal hypothyroidism due to drop in LH and FSH levels, the Leydig and Sertoli cells, respectively are less stimulated to differentiate into mature cells, negatively affecting spermatogenesis. This increases the number of cells in the testes but decreases the number of mature cells.

Poppe et al. in 2018 investigated the impact of TAI on pregnancy outcomes in infertile women undergoing ICSI treatment, excluding IVF or IUI cycles, accounting for 4 studies for a total of 1855 ICSI cycles (of them, 290 with TAI) reporting no increased risk of early miscarriage 62. A meta-analysis investigating the effect of levothyroxine treatment in TAI-positive women undergoing ART denied any positive impact on that the miscarriage rate; however, levothyroxine decreased the miscarriage rate if subclinical hypothyroidism was present 63 suggesting that this condition per se may be detrimental 9, 64. Specific information regarding the effect of thyroid function on controlled ovarian hyperstimulation (COH) is limited, mainly due to the absence of randomized controlled trials. When it comes to male fertility, a range of factors contribute to overall reproductive health, and one that often goes under the radar is thyroid function. The thyroid gland, known for regulating metabolism and energy, also plays a crucial role in the male reproductive system. Proper thyroid function ensures optimal sperm production and sperm quality, while imbalances in thyroid hormone levels—whether too high or too low—can lead to fertility issues.

The results of this in vitro study could have a clinical application in patients with idiopathic infertility, clarifying the role of thyroid function on male fertility. The thyroid gland is responsible for secreting hormones that regulate metabolism, growth and development. Among these hormones, thyroxine (T4) and triiodothyronine (T3) are essential for maintaining normal reproductive function.

Your thyroid gland

You will require regular thyroid function tests in pregnancy to ensure you are on an appropriate dose. If you have been treated for Graves’ disease with radioactive iodine or surgery in the past, or need antithyroid drugs during pregnancy, you may have Graves’ antibodies (also known as TSH receptor antibodies (TRAb)), which can cross the placenta. On rare occasions these can cause temporary hyperthyroidism in the baby during pregnancy and after birth, but this is treatable.

References

Women may have longer or heavier periods, which can cause anaemia, or your periods may stop completely. Men’s fertility may also be affected and they may be less likely to father a child if their thyroid hormone levels are low. However, once you are taking medication (levothyroxine tablets) and your thyroid hormone levels are back to normal your chances of becoming pregnant, or fathering a child, should improve dramatically.