Women who do sport professionally are more prone to the risk of functional hypothalamic amenorrhea (FHA). Menstrual disorders are also becoming more common among women who do recreational sports. In this article I would like to write about the possible reasons and consequences of FHA. In the next part I will suggest some solutions, which support regulating the monthly cycles with high physical activity and low level of body fat.
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Endocrine and metabolic disorders among women with FHA
In case of functional hypothalamic amenorrhoea (FHA), there is a decrease in releasing gonadotropin-releasing hormone (GnRH) by the hypothalamus, therefore, there is less luteinizing hormone (LH) and follicle-stimulating hormone (FSH) released by the hypophysis, which worsens the stimulation of the ovaries and decreases the secretion of estrogens. According to estimate, FHA is responsible for 20-30% of cases of secondary amenorrhea (lack of menstruation for longer than 3 months). The frequency of occurrence of such condition is increased among women who workout regularly. In this group FHA may be one of the symptoms of so-called female athlete triad, which is a condition including nutrition disorder, lowering bone mineral density and menstrual disorder .
Next to the suggested disorders on the hypothalamus-hypophysis-ovaries line among women with FHA, there usually occur many other endocrine and metabolic dysfunctions which influence the functioning and the homeostasis of the whole body. You can find the disorders on the hypothalamus-hypophysis-thyroid line, as well as the hypothalamus-hypophysis-adrenals line, which lead to lower level of triiodothyronine (T3) and higher level of reversed triiodothyronine and cortisol. In the fitness context, comparing women with FHA to women with regular menstruation, higher level of pre- and after-workout cortisol was observed [2, 3]. Such disorders seem to have direct influence on decreased secretion of GnRH by hypothalamus, and therefore, the functioning of the hypothalamus-hypophysis-ovaries line .
The reasons for FHA to occur
There are many substances which are engaged in the regulation of menstrual cycle. The following substances are probably the most important: kisspeptin, neuropeptide y, beta-endorphin, leptin and ghrelin [4, 5]. Some of these substances inform the brain about the amount of supplied energy, volume and intensity of workouts, amount of time spent on sleeping, as well as the amount of energy stored in a form of body fat.
From the evolution point of view, the reproductive functions may be “switched off” temporarily, which is the adaptation to the adverse conditions, where getting pregnant could make it hard to survive. There are many factors which the body may read as a threat for the life of the mother and the baby.
Initially, low body fat was supposed to be one of these factors. It was suggested in the hypothesis connected with the body composition, that the level of body fat below 22% leads to reduction of releasing GnRH, and therefore, to the deregulation of menstrual cycles. Despite common acceptance in the medical environment, this hypothesis has no strong support in the experimental research. The observation evidence is also not so convincing.
According to the second most common hypothesis, high volume/intensity physical workout is a stress factor, which can decrease the release of GnRH by interfering the hypothalamus-hypophysis-adrenals and hypothalamus-hypophysis-thyroid lines. This hypothesis has also been questioned and some researches do not support its validity.
Another hypothesis, which points out that the menstrual disorder among working out women are mostly connected with inadequate to the needs supply of energy, has found larger support in literature. Going back to the evolutionary consideration, the total energy cost of pregnancy is 70,000-80,000 kcal. The circumstances which suggest lack of possibility of assuring proper amount of calories and nutrients for the fetus development, according to this thesis, may foster “switching off” the reproductive functions .
The occurrence of the factors mentioned above separately does not cause menstrual disturbance in many cases. Therefore, there are different results of research. However, when these factors come together, they show the synergistic effect . In other words, the menstrual disturbance among women who desire to achieve fitness shape can be connected with the compensation of the negative effects of at least few stress factors: excessive calorific and nutritious restriction, low level of body fat, high volume and/or intensity of workouts, and insufficient amount and quality of sleep; especially if the additional factor is strong psycho-social stress. In my opinion, this hypothesis seems to be the most convincing.
The consequences of FHA
Increased risk of injuries (connected or not connected with bone fractures) are the most commonly discussed consequences of FHA, which are probably caused mainly by lowering the level of the insulin-like growth factor type 1 . I will not focus on that matter in this article, because I will pay attention to other aspects.
Many tests that have been run recently have showed that hypoestrogenism, characteristic for women with FHA, may lead to the dysfunction of the endothelium of blood vessels, decreasing bio-activity of nitrogen oxide, as well as disadvantageous changes in the lipid profile . Endothelium is the inner layer of blood vessels and is very important for the regulation of the tension of these vessels by releasing the substances opening them, such as nitric oxide. In one of the tests with 35 women who do endurance sports and 12 women leading sedentary life, the worst values of artery dilatation in response to the flow-mediated dilatation (FMD) were noticed among women with FHA. At the same time, women with FHA had worse lipid profile (larger concentration of total cholesterol and LDL) comparing to physically active women with regular menstruation or those with rare menstruation (oligomenorrhea – length of cycles over 35 days) . The ultrasound assessment of the artery dilatation in response to the flow-meditated dilatation (FMD) is one of the most accepted method of checking the endothelium functions and can be used to forecasting the future heart-vessel episodes.
In another test, FMD was defined among 26 young volleyball players and 10 women leading sedentary life. Once again, women with FHA had the lowest values of FMD. At the same time, it was observed that the level of estradiol was positively correlated with the results of FMD – the lower level of estradiol, the worse FMD results. It was also proved that resigning from intensive workouts by the tested women increased the level of estradiol and improved the FMD value .
I can also add, that the adverse lipid profile and the FMD values in case of women with FHA can be related to the low level of T3 (it increases the activity of the LDL receptors) and T4 (it supports creating levomefolic acid, which increases the level of nitrogen oxide).
The presented results are even more alarming, because there haven't been many researches concerning the possibility of improving the results of FMD among women with FHA. In two tests, done with runners and dancers, the supplementation of large doses of folic acid caused promising results. However, there's no doubt that this area needs further research, especially the connection of high frequency of occurrence of the mutation of C667T gene methylenetetrahydrofolate reductase (MTHFR – it makes it possible to transform folic acid into an active form, which is the mentioned levomefolic acid) [11, 12].
Hypoestrogenism and increased level of cortisol, by reacting onto many neurotransmiters and neurosteroids, may lead to depressive and anxiety symptoms, as well as the difficulty with coping with everyday stress among women with FHA . The mood disturbance, together with low levels of estrogens and androgens may negatively influence the sexual functions and libido .
What's more, the long-lasting lack of menstruation may lead to infertility. At the same time, pregnancy for women with the FHA history needs special care because of the increased risk of miscarriage or premature delivery .
To sum up
The exogenous estrogen-progestogen therapy, which is often advised in case of menstruation disturbance, shows limited action and efficiency. Functional hypothalamic amenorrhea is a very complex problem connected with the occurrence of many endocrine, metabolic and psychological disorders. For that reason, using more complex solutions than the estrogen-progestogen mono-therapy will be necessary.