Hormones in Flux: Navigating Menopause

During menopause, there are changes in hormone levels. The levels of sex hormones like estrogen instance, after a woman's final menstrual cycle, the concentration of Follicular Stimulating Hormone (FSH) in the blood increases by an average of 68%. At the same time, there's a decrease in estradiol by about 60% and estrone by 32%, compared to levels 1–6 months before the final menstrual cycle (4).

The drop in estrogen during menopause is linked to lower levels of growth hormone (GH), insulin-like growth factor (IGF-1), and dehydroepiandrosterone (DHEA). This hormonal shift leads to reduced muscle protein synthesis and an increase in factors that break down tissues, such as pro-inflammatory cytokines like tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6) (3-5). After the initial sharp hormone changes, there is a more gradual decline in the early post-menopausal period.

Among the four types of estrogen, estradiol (E2) is the most common and potent during a woman's reproductive years. E2 plays a crucial role in maintaining muscle health and managing inflammatory responses (6). Estrogen receptors are present in skeletal muscle fibers and contribute to muscle regeneration by stimulating muscle satellite cells, which repair and maintain muscle integrity after exercise-induced damage (7) (8). Estradiol also influences the production of growth hormone (GH) and insulin-like growth factor 1 (IGF-1), and it helps modulate both local and systemic inflammation responses (9), (10).

When estrogen levels decrease during menopause, there is a corresponding increase in pro-inflammatory cytokines like interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-α). Post-menopausal women typically have lower estrogen levels and higher levels of TNF-α compared to pre-menopausal women (11). These changes contribute to increased fat accumulation, compromised muscle function (12) (13) (14), and a condition known as sarcopenia, characterized by muscle loss (15) (16). Research shows that estradiol helps reduce inflammation and muscle breakdown after exercise. It does this by stopping the release of substances that cause muscle damage (17) (18) (19).

Around menopause, there is a significant drop in estradiol levels, from an average of 383±363 to 182±163 pmol/L over six months (2). This decline continues moderately over the next few years, with estradiol (E2) levels reaching 148 pmol/L, by approximately 3.5 years post-menopause (2). According to Best Practice Advocacy Centre New Zealand (bpacnz), post-menopausal estradiol levels are typically below 200 pmol/L (20).

Aside from estrogen, progesterone is another essential female reproductive hormone. Production of progesterone by the ovaries stops after the final menstrual period, contributing to the loss of muscle function, muscle mass, and sarcopenia (21). In the years leading up to menopause, there is a marked decrease in ovulation cycles in the six years before menopause. Progesterone concentrations also decline significantly from approximately 27.3±9.95 nmol/L to 22.4±15.1 nmol/L in the months leading up to menopause (2). Post-menopausal women typically have very low serum progesterone levels (≤ 2 nmol/L) (2).

FSH is a hormone produced by the pituitary gland, which is located at the base of the brain. In women, it stimulates the growth and development of ovarian follicles (structures in the ovaries that contain eggs) during the first half of the menstrual cycle. Rising FSH levels trigger the release of estrogen from the ovaries, which helps to prepare the uterus for a potential pregnancy. After menopause, FSH levels tend to rise significantly as the ovaries no longer produce estrogen and eggs, signaling the end of reproductive function in women. Before menopause, follicular stimulating hormone (FSH) levels fluctuate between 3-25 IU/L and rise to over 20 IU/L post-menopause (20).

LH is also produced by the pituitary gland. In women, LH works alongside FSH to regulate the menstrual cycle and ovulation. During the menstrual cycle, LH levels surge just before ovulation, triggering the release of a mature egg from the ovary (ovulation). Following ovulation, LH helps to stimulate the empty follicle in the ovary to produce progesterone, which prepares the uterus for potential pregnancy. After menopause, LH levels may remain elevated as the pituitary gland attempts to stimulate the ovaries to produce hormones, despite the decline in ovarian function. Luteinizing hormone (LH) levels range from 2-75 IU/L before menopause and exceed 15 IU/L post-menopause (20).

Together, FSH and LH play crucial roles in regulating reproductive function in women throughout their fertile years. The changes in their levels during menopause reflect the natural transition from reproductive to non-reproductive phases of life, impacting hormone levels and menstrual cycles accordingly. Approximately 4.75 years before menopause, there is a significant increase in FSH and LH levels, which then decline following menopause.

Although less discussed in the context of menopause, testosterone also plays a role in maintaining muscle and promoting muscle growth in women. Circulating free testosterone, which is metabolically active, decreases with age and particularly in the first few years after menopause, potentially accelerating muscle mass loss (22) (23). Research indicates that testosterone levels decline by about 15% in the two years around menopause but stabilize in the years following (2).

Growth hormone (GH) and Insulin-like Growth Factor 1 (IGF-1) are important hormones that work together to regulate growth and development in our bodies. GH is also produced by the pituitary gland. Its primary role is to stimulate growth in children and adolescents, helping them to grow taller and develop properly. In adults, GH continues to play a role in regulating body composition, metabolism, and muscle growth. It helps to maintain healthy muscle and bone mass, promotes fat breakdown for energy, and supports overall physical fitness. GH levels typically decrease with age, which can contribute to decreased muscle mass, increased body fat, and reduced bone density.

IGF-1 is produced mainly in the liver in response to GH stimulation. It acts as a mediator of the growth-promoting effects of GH. Optimal levels of IGF-1 are important for maintaining muscle strength, bone density, and overall physical function. Together, GH and IGF-1 form a critical axis in our bodies that regulates growth, development, and maintenance of tissues throughout our lives. Their decline with age underscores the importance of healthy lifestyle choices and potentially hormone replacement therapy in maintaining optimal function and vitality.

 Both growth hormone (GH) and insulin-like growth factor 1 (IGF-1) decrease with age and following menopause, impacting body composition by increasing fat mass, especially around the abdomen, and decreasing lean muscle mass (24). Studies have found significantly lower plasma levels of IGF-1 in post-menopausal women compared to pre-menopausal women (25). Mean 24-hour growth hormone concentrations are also significantly lower in post-menopausal women (26).

Dehydroepiandrosterone (DHEA) is a hormone naturally produced by our bodies, especially during younger years. It plays several important roles, including helping to build and maintain muscle mass, supporting our immune system, and even contributing to our mood and overall sense of well-being.

Interestingly, DHEA can also be converted into other hormones, such as estrogen, in certain tissues like muscles. This conversion can have additional effects, such as helping to maintain bone density and potentially impacting overall health as we age.

Dehydroepiandrosterone (DHEA) production peaks between the ages of 25-35 years and gradually declines thereafter, especially during menopause. This decline is associated with reduced muscle mass and physical performance. DHEA can be converted into estrogens like estradiol in tissues such as skeletal muscle, exerting estrogenic effects (1). DHEA sulfate (DHEAS), the sulfated conjugate of DHEA, also declines with age and is associated with the onset of age-related chronic diseases (27).

During menopause transition there is a lot going on with our bodies some of which we have no control over. Hormone Replacement Therapy can help attenuate the changes in some hormones but it is not for everyone and should be discussed with your medical practitioner. Further, lifestyle (diet and exercise) can help to attenuate some of the influences menopause has on our health, body composition and performance. Fred nutrition aims to bring you evidenced based advice to optimise your health, body composition and to help you reach your goals.