Hypothyroidism and Male Infertility

ben bunting BA(Hons) PgCert Sport & Exercise Nutriton  Written by Ben Bunting: BA(Hons), PGCert.

The thyroid is a butterfly-shaped gland that secrets multiple hormones together called thyroid hormones.

Among them, thyroxine is the most vital. These hormones play a critical role in growth and metabolism. In addition, it plays a vital role in brain development in children.

In this article we shall cover the following key points:

  • Hypothyroidism
  • Research
  • Sperm health
  • Sexual function
  • Treatment
  • Hormones
  • Is it manageable?
  • Conclusion


It appears that both hyper and hypoactivity of this gland are not rare.

However, in the case of hypothyroidism, it slows down the basal metabolic rate which means a significant slow down of metabolic activity in the body, resulting in weight gain, potential obesity, and water retention in adults. 

Side effects

Hypothyroidism causes widespread changes in the body, these can look like:

  • higher level of fatigue
  • constipation
  • dry skin
  • muscle weakness
  • dyslipidemia
  • pain and stiffness of joints
  • depression
  • impaired memory

The longer the person living with hypothyroidism, the more severe would be the symptoms.


hypothyroidism and male infertility

However, in many cases, the so-called sub-clinical hypothyroidism is not rare. In such cases, infertility or sub-fertility could often be the primary presenting sign.

Early researchers did not realize that the thyroid can significantly impact male fertility. However, things have been changing fast, and it is evident now that the thyroid affects almost every parameter of male fertility.

Thus, hypothyroidism not only reduces male fertility but may considerably reduce male sexual activity.

Thus, for example, one of the pilot studies in 24 patients found that hypothyroidism adversely affected both sperm quality and erectile function.

In addition, it may considerably worsen sperm motility, and this adverse impact is directly proportional to the severity of the condition.

Additionally, it appears that hypothyroidism may have a particularly negative impact on sperm quality.

➡️READ: Natural treatments for male infertility

Further things are made worst by the adverse effects of hypothyroidism on sexual activity, which is not limited to erectile dysfunction. Thus, it may also cause delayed ejaculation and a significant decline in libido.

Despite the known influence of hypothyroidism on sexual activity and sperm quality, it has remained a neglected topic.

There are many studies on animals, but they are rarely applicable to humans. Nonetheless, in the last couple of decades, there have been some large-scale clinical trials confirming that hypothyroidism does cause a significant decline in male fertility.

Thus, a study by Krassas et al. in 25 patients found that hypothyroidism affected sperm morphology or structure adversely, and it also resulted in reduced motility. However, the study found only the marginal effect pointing more at sub-fertility than complete infertility.

Similarly, a study by Vaghela et al. in 2016 found that hypothyroidism is associated with a decline in sperm volume, motility, head abnormality, or morphological changes.

These changes were enough to cause fertility-related issues, but perhaps not absolute infertility.

Sperm health 

So, what do we get from some of the clinical studies done to date regarding the effect of hypothyroidism on male fertility?

It would be correct to say that hypothyroidism negatively affects male fertility, causing changes in sperm morphology, count, and motility.

However, these changes are more likely to cause sub-fertility than absolute infertility.

Sexual function

Additionally, in some cases, things might be made worse due to changes in sexual health in general, like reduced sexual function, desire, and erectile function.

Together these changes may cause infertility in some individuals.

However, fortunately, hypothyroidism, once diagnosed, is also readily managed. It means that many of the changes in male fertility are possible to reverse in a short time.


Generally, once the hypothyroidism treatment is started, it would take a few weeks for male fertility to normalize.

However, complete revival may take much longer. Since, in practice, reversing male fertility is much more challenging than treating hypothyroidism or reversing changes caused by low thyroid hormone.

To understand why treating hypothyroidism would not necessarily result in brisk reversal of male infertility, one needs to know how low thyroid hormones cause fertility-related issues.


Studies show that in hypothyroidism, T3 and T4 levels are reduced, which ultimately causes a decline in SHBG concentrations. This results in decreased circulating testosterone levels in the body and a slowdown in spermatogenesis.

However, the problem is that hypothyroidism is a chronic disorder that is often diagnosed quite late.

By the time a person is diagnosed with hypothyroidism, prolonged low testosterone levels result in severe changes in testicular histology or cell structure.

Not only that, hypothyroidism may even reduce the diameter of the seminal duct, testicular size, changes in prostate weight, progressive loss of sperm motility, changes in sperm transit times, and much more. It also significantly increases oxidative stress in testicles.

As one can understand that many of these changes in the genital system and testicles are pretty challenging to reverse, thus requiring prolonged treatment.

Comorbid factors

Thus, after the diagnosis of hypothyroidism, doctors would not only need to treat thyroid issues, but they would need to manage hypogonadism and other changes in sexual health.

This may also involve normalizing the production of LH and FSH levels and much more.

Thus, treatment would also require focusing on the hypothalamic-pituitary-gonadal axis.

Many people would like to know if infertility caused by hypothyroidism is reversible or not.

Is it manageable?

The answer is that perhaps it is manageable and reversible in most cases. However, lots would depend on the severity and duration of the condition.

Prolonged and unmanaged hypothyroidism may cause some irreversible changes in the reproductive organs.

Additionally, outcomes would also depend on the age of the patient. Older adults are generally poor responders to the therapy.

Nevertheless, it is worth knowing that hypothyroidism is managed effectively. Doctors can bring back the thyroid hormones to their normal level in a few weeks.

However, it may need a much longer time when it comes to the revival of fertility. It is not just about treating hypothyroidism but also managing other changes in the reproductive system that need relatively longer treatment.


Finally, it is worth understanding that although hypothyroidism is a highly treatable condition, the patient may need to take medications for a long.

Often lifelong, as it is manageable but cannot be cured. It is managed by continually taking medications that ensure adequate thyroid hormones secretion.