Hypothyroidism and fertility
What is hypothyroidism?
Hypothyroidism refers to the insufficient function of the thyroid gland, resulting in the production of inadequate levels of thyroid hormone. Hashimoto’s thyroiditis is the most common underlying cause of hypothyroidism in women.
How does hypothyroidism affect fertility in women?
Thyroid dysfunction can negatively impact fertility, both the ability to conceive and the ability to a fetus to term. The presence of autoimmune antibodies, with or without thyroid disorder can also impact fertility.
Hypothyroidism can cause menstrual disorders, affect the occurrence of ovulation and egg quality, impair the implantation of the embryo and increase the risk of miscarriage and premature birth.
More specifically, women with hypothyroidism experience a disturbance of progesterone levels in the second half of the menstrual cycle- (post-ovulation). This hormonal disorder (luteal disruption) affects the quality of the endometrium during implantation of the fetus and it may be characterized by lengthening or shortening of the menstrual cycle or menstruation, such as oligomenorrhea or menorrhagia.
How does hypothyroidism affect male fertility?
Thyroid hormones affect the testicles in different ways by affecting different cell types (Leydig, Sertoli, germ cells). Decreased production of thyroid hormones can lead to sperm disorders, such as decreased progressive motility, disturbances in the access of the epididymis and its secretory activity, as well as the volume of ejaculation.
The most common sperm disorder in the case of hypothyroidism is teratozoospermia. This means that the morphology index of the sperm is reduced compared to normal and in fact it is inversely related to the levels of T4, thus reducing the chance of normal fertilization of the egg, because it affects the ability of the sperm to enter the egg (acrosomal reaction).
How is the diagnosis made?
Symptoms such as:
The diagnosis is made by a simple blood test and includes measurements of the levels of all thyroid hormones, that is, TSH, T4, T3, rT3, as well as the thyroid antibodies levels. For optimal fertility, TSH levels should be between 1 and 2.5 mIU / L.
However, many women remain undiagnosed, especially those with subclinical hypothyroidism, which is not a biological disorder, but a clinical phenomenon with a mild increase in TSH without any other disorder or symptom.
What is the treatment for hypothyroidism?
In many cases, most women with primary infertility are unaware that they may have subclinical hypothyroidism.
Oral treatment with Levothyroxine restores normal hormonal balance, helps to normalize the menstrual cycle, and increases the chances of spontaneous conception. More specifically, it replaces thyroxine (T4), in case the body does not produce enough of it.
Administration or diet supplementation with selenium and vitamin D3 can also help the thyroid gland function better.