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Some thyroid changes, such as hypo and hyperthyroidism, can interfere with the menstrual cycle, since there is an imbalance in the levels of T3, T4 and TSH hormones, which are hormones that directly influence the functioning of the reproductive system female, including in the concentration of circulating estrogen and progesterone.
Thus, in the case of hypothyroidism, it is possible for the woman to have a more irregular menstrual cycle, with greater flow and more cramps, while in hyperthyroidism, it is more common to have a decrease in menstrual flow and, in some cases, amenorrhea, which is the absence of menstruation.
It is important that the gynecologist is consulted if any change in the menstrual period is observed, as tests may be requested to identify the cause and initiate the most appropriate treatment.
How the thyroid affects menstruation
Possible changes that can happen in the menstrual cycle due to changes in thyroid functioning are:
Hypothyroidism is characterized by increased circulating TSH concentration and decreased levels of T3 and T4, which can lead to the following changes:
- Appearance of menstruation before age 10,which can happen because increasing TSH has a small effect similar to the hormones FSH and LH, which are responsible for regulating menstruation.;
- Early menstruation,that is, a woman who had a 30-day cycle may have a 24-day cycle, for example, or menstruation may come out of time;
- Increased menstrual flow,called menorrhagia, requiring you to change the tampon more often throughout the day and, in addition, the number of days of menstruation may increase;
- More severe menstrual cramps,called dysmenorrhea, which causes pelvic pain, headache and malaise, and pain relief may be required.
Another change that can happen is the difficulty in getting pregnant, because there is a decrease in the luteal phase. In addition, galactorrhoea, which consists of the release of 'milk' from the nipples, can also occur, even if the woman is not pregnant.
Hyperthyroidism occurs when there is a lower amount of circulating TSH and a normal or higher concentration of T3 and T4, which can cause:
- Delayed 1st menstruation,when the girl has not yet had her menarche and already has hyperthyroidism in childhood;
- Delayed period,due to changes in the menstrual cycle, which can be more spaced, with a longer interval between cycles;
- Decreased menstrual flow,that can be noticed in sanitary pads, because there is less bleeding per day;
- Absence of menstruation,which can last for several months.
After having surgery to remove a part of the thyroid, changes in menstruation may also occur. Right after the surgery, while still in the hospital, heavy bleeding may occur even if the woman is taking the continuous pill normally.
This bleeding may last 2 or 3 days, and after 2-3 weeks there may be a new period, which may arrive by surprise, and this indicates that the half of the thyroid that remained is still adapting to the new reality, and it still needs to adjust for the amount of hormones it needs to produce.
When to go to the doctor
An appointment with a gynecologist should be made if the woman has the following changes:
- You are over 12 years old and have not yet had your period;
- Going more than 90 days without menstruation, and if you are not taking the continuous pill, nor are you pregnant;
- Experiencing an increase in menstrual cramps, which prevents you from working or studying;
- Bleeding for more than 2 days, totally outside the menstrual period;
- Menses become heavier than usual;
- Menstruation lasts longer than 8 days.
The doctor may request TSH, T3 and T4 tests to evaluate thyroid hormones, in order to check if there is a need to take medication to regulate the thyroid, so that menstruation will be normalized. Discover the tests that evaluate the thyroid.