The Effects of Male Thyroid Conditions on fertility
In our last infertility article, we discussed thyroid conditions and their effects on the female reproductive cycle and fertility. We learned that an underactive thyroid (hypothyroidism) or overactive thyroid (hyperthyroidism) can have a very negative impact on the reproductive cycle, causing periods to be very heavy, light, irregular, infrequent, or even completely absent. Thyroid conditions can also cause issues with implantation, maternal health, and fetal health. These negative effects have an impact on a woman’s ability to become pregnant and/or have a healthy pregnancy to term.
Though thyroid conditions are often thought to be conditions affecting women, men can also be affected by thyroid conditions. Also, like women, male hypothyroidism can affect male fertility. Though women are 5 to 8 times more likely to have hypothyroidism than men (1), 3-16% of men may have hypothyroidism, with the risk of the condition increasing as age increases (2). Symptoms of hypothyroidism tend to be similar between men and women, including fatigue, depression, constipation, cold intolerance, weight gain, and dry skin. Additionally, hypothyroidism may cause hair loss, low testosterone, muscle weakness and cramps, and sexual dysfunction (3).
In regard to hyperthyroidism, women are 2 to 10 times more likely to develop the condition; however, men can develop an overactive thyroid as well. The most common cause of hyperthyroidism in men is Graves’ disease, but other causes may include nodules in the thyroid gland, inflammation of the thyroid, and Plummer’s disease, which is also known as toxic nodular goiter. Symptoms of hyperthyroidism may include heart palpitations, irregular heartbeat, unexpected weight loss, nervousness, fatigue, irritability, heat/cold sensitivity, more frequent bowel movements, hair thinning, muscle weakness, osteoporosis, gynecomastia (male breast enlargement), and/or tremors. In terms of sexual health, hyperthyroidism can cause erectile dysfunction, low sperm count, low testosterone, and decreased sperm motility.
Hypothyroidism and hyperthyroidism can both affect a man’s fertility. In a study examining males with both hyper- and hypothyroidism, researchers found that decreased libido, delayed ejaculation, and overall erectile dysfunction were problematic. However, after hypothyroid men were treated with L-thyroxine and hyperthyroid patients were treated with methimazole to normalize TSH values, far fewer patients complained of these issues (4), showing that thyroid treatment can be largely successful.
We describe more specifically some fertility issues that thyroid conditions can cause in men below.
Impaired Spermatogenesis
Spermatogenesis is the process of sperm cell development in the male testes, which certainly plays a large role in fertility and successful pregnancy.
Testosterone is needed to perform adequate spermatogenesis and to maintain sperm count. It’s also needed for sperm motility. Thyroid hormones regulate semen quality through adjusting serum testosterone levels. Thyroid hormones also act alone or in combination with follicular stimulating hormone (FSH) and/or luteinizing hormone (LH) to modulate testes development, testosterone synthesis, and spermatogenesis, which has an impact on semen quality (5). Thyroid receptors can be found in various parts of the testes.
In hypothyroidism, there are decreased T3 and T4 levels circulating throughout the body and reduced sex hormone binding globulin. These factors can affect sperm production, causing low sperm count, low sperm motility, and low ejaculate volume. Additionally, hypothyroidism is also associated with a decrease in tube diameters in the testes as well as reduced size in testicular, epididymal, and prostate weight. This can affect sperm development, sperm motility, and transit time through the epididymis (5). Hypothyroidism is also often associated with problematic sperm morphology, which is the size and shape of the sperm (6).
Hyperthyroidism causes increased T4 levels in addition to altered LH and FSH responsiveness. These issues can affect the development and functioning of male reproductive tissues, including a reduced diameter of the seminiferous tubule and impaired or delayed spermatogenesis. Hyperthyroidism may also impact mitochondrial activities in spermatozoa, affecting sperm motility (7). Overall, hyperthyroidism is associated with reduced semen volume and density, sperm motility, and sperm morphology (8).
Impaired Nitric Oxide Activity
Nitric oxide is a molecule that is produced in the body and is crucial for optimal function because of its role in vasodilation, which is when the muscles of the blood vessels relax. Vasodilation allows the inner vessels of the blood cells to become wider and increase circulation throughout the body. The production of nitric oxide increases vasodilation, which then allows nutrients, blood, and oxygen to circulate smoothly and efficiently through your body.
This process of vasodilation is also crucial to sexual health, as it is necessary to attain and sustain an erection (9). Nitric oxide production is mediated by the thyroid (10). Hypothyroidism is associated with reduced nitric oxide gene transcripts, which may explain a mechanism behind erectile dysfunction associated with hypothyroidism (11).
Impaired Sexual Drive
A male’s thyroid condition can also significantly affect his sex drive, also referred to as low libido. Lack of thyroid hormones can affect free testosterone concentrations in men (12), and low testosterone may contribute to low libido (13). When thyroid hormone production is typical, it stimulates the hypothalamus, which produces GnRH (gonadotropin-releasing hormone). GnRH then signals to the pituitary gland to produce LH, and LH, in turn, signals the testes to produce testosterone. This process can be affected greatly if there is a lack of thyroid hormone, which can result in low testosterone. While low testosterone isn’t the only contributor to low libido (and not every male with low testosterone has low libido), it may certainly be a factor (13).
Thyroid Autoimmunity, Oxidative Stress, and Male Fertility
You might remember that an autoimmune condition occurs when there is a misguided immune system response to something in the body that is targeted as a threat. In thyroid autoimmune conditions, like Hashimoto’s and Graves’ disease, the immune system targets and attacks the thyroid. This immune system breakdown leads to increased oxidative stress, which is an imbalance between antioxidants and free radicals. The oxidative stress can then affect other parts of your body, including parts of the male reproductive system. We discuss the connections of thyroid autoimmune conditions and infertility below.
Testicular Dysfunction
Thyroid hormones play a big role in the development and function of the testicles, including the function of the Leydig cells and Sertoli cells (14). Leydig cells are adjacent to the seminiferous tubules (the tubes where sperm is produced) in the testicles, and they produce testosterone when there is sufficient LH. Sertoli cells are part of the seminiferous tubules and are involved in spermatogenesis when FSH is present. Sertoli cells have FSH receptors on their membranes.
A compromised thyroid state can have a large impact on the testicles. Because the testes have a poor antioxidant defense system and have a high unsaturated fatty acid content, they are at higher risk of oxidative injury. A compromised thyroid status can lead to oxidative stress in the testicles, which will lead to dysfunction in the testicles. (15)
Thyroid Autoimmunity’s Effects on Men
When a person tests for high levels of Thyroid peroxidase antibodies (TPO antibodies) or thyroglobulin antibodies, that is an indicator for the presence of thyroid autoimmune conditions, such as Hashimoto’s or Graves’ disease.
There are connections with the presence of these antibodies and infertility markers in men. Generally, elevated TPO antibodies are significantly correlated with pathozoospermia, which is a difference in the normal values of sperm quantity, motility, and morphology. Specifically, elevated TPO antibodies are significantly correlated with asthenozoospermia, which is reduced sperm motility. (16)
Sperm Antibodies
When a person has sperm antibodies, their body is mistaking sperm as an enemy, targeting it, and attacking it. Both men and women can have sperm antibodies. For men, a prostate infection or testicle injury may set off an immune response to sperm. For women, they may start creating sperm antibodies if they have an allergic reaction to semen. While you can still conceive with sperm antibodies, they can make the process more difficult. (17)
Research has found that infertile men with sperm antibodies also often have thyroglobulin antibodies (a marker for thyroid autoimmunity), suggesting a connection between the two issues. This research suggests that men who have infertility should be screened for autoimmune thyroid conditions. (18)
As you can see, thyroid conditions can affect male fertility issues along with female fertility issues. It’s important to check a male’s thyroid status, especially if he and his partner are struggling with infertility. We specialize in getting to the root cause of thyroid health and would love to help. Please call our office with any questions.
References:
https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/415184
https://biomedpharmajournal.org/vol11no1/thyroid-disorders-and-semen-quality/
https://academic.oup.com/endo/article-abstract/136/10/4182/3036363
https://www.webmd.com/men/how-low-testosterone-can-affect-your-sex-drive
https://www.sciencedirect.com/science/article/pii/B9780128125014000158
https://www.webmd.com/infertility-and-reproduction/fertility-antisperm-antibodies