In this article we are going to look at the hormone progesterone, specifically looking at low levels of progesterone. We explore how progesterone is made, common symptoms, testing considerations, some of the potential causes and some hints and tips to help support progesterone levels/balance.
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What is progesterone and where is it made?
Progesterone is seen as a female hormone, although men do have progesterone as well to help with sperm development. In females it is produced predominantly by the corpus luteum in the ovaries, then small amounts are also produced in the ovaries themselves and the adrenal glands.
One of the main roles of progesterone is to prime the uterus for pregnancy. It does this by thickening the lining of the uterus, think of it as making a comfy bed for the fertilised egg. If no egg fertilisation occurs, then progesterone levels reduce, and menstruation begins. If one falls pregnant then the progesterone helps to maintain the healthy uterine lining throughout pregnancy, stimulating the growth of blood vessels that supply the lining of the womb and stimulating glands in the endometrium to secrete nutrients that nourish the embryo.
Once the placenta is established in pregnancy, around 8-12 weeks, the placenta takes over producing progesterone and will continue to do so throughout pregnancy assisting with the foetal development, growth of breast tissue, preventing lactation, and strengthening the pelvic wall muscles prior to labour. Progesterone steadily increases throughout pregnancy.
When considering progesterone production by the corpus luteum, this is triggered by a surge in luteinising hormone by a gland in our brain called the pituitary gland. This typically occurs around days 12-16 and stimulates the release of an egg from the ovary (ovulation), and this forms the corpus luteum which then releases progesterone.
Progesterone levels can also impact areas such as digestive health and has been shown to impact on motility, thus stool consistency. Not only that, it is also involved in maintaining healthy bones, brain and blood vessels.
What are the symptoms of low progesterone in pre-menopausal females?
There are a variety of symptoms associated with progesterone insufficiency, these include:
- Acne
- PMS
- Joint Pain
- Irregular menstrual cycle
- Anxiety
- Headaches
- Cramping
- Infertility
- Swollen breasts
- Spotting before period
- Foggy thinking
- Reduced libido
- Mood swings
- Depression
- Long or heavy periods
- Short menstrual cycles
- Hot flashes
- Water retention
- Saggy or loose skin
Because the balance of estrogen and progesterone is so important, if you have unusually low progesterone comparative to estrogen levels this can lead to estrogen dominant symptoms. You may not need low progesterone for this to happen, it may be that your estrogen is too high. In which case, addressing estrogen dominance may be the priority.
Because of the overlap with estrogen dominance and low progesterone, testing is crucial to understand exactly what is going on prior to exploring treatment strategies.
Testing considerations for hormones in females
Testing should include the following blood tests:
- Luteinising hormone (LH)
- Follicle stimulating hormone FSH)
- Prolactin
- Estradiol (E2)
- Sex Hormone Binding Globulin (SHBG)
- Progesterone
- Testosterone
Progesterone testing is only necessary if you are menstruating, and in the case of progesterone, this should be assessed during the mid-luteal phase of your menstrual cycle, roughly 7 days after ovulation. For a lot of people this is around day 20-22 of your cycle, however, this can vary one person to another.
Other tests may include urine hormone analysis, again this can be performed during the mid-luteal phase of one’s cycle, however, some labs also offer month long assessments using dried urine or saliva samples. With these tests you can assess estrogen and progesterone levels, usually 2-3 days between each measurement to build up a picture of your estrogen and progesterone levels throughout your cycle. These can be extremely useful, but should be done in addition to the blood tests listed above and not instead of.
Testing is used to help determine the cause of the low progesterone. If prolactin is high and LH is low, then the focus needs to be on addressing this area. If LH is good but progesterone levels are low, then this is a completely different approach. Likewise, LH may be good, progesterone good, but estrogen levels are very high, in which case another approach is required.
This is why testing and an individualised approach is so important. You can have symptoms of low progesterone, but a variety of treatments are not going to work to support a healthy level or balance of progesterone because they are not dealing with underlying causes.
What causes low progesterone in pre-menopausal females?
Elevated prolactin
Raised levels of prolactin can result in the inhibition of ovulation and subsequently lead to infertility. If prolactin is too high then ovulation cannot occur, thus increases in progesterone production following ovulation does not exist.
Elevated prolactin can occur as a result of a number of factors, here are a few common ones:
- High levels of emotional/physical stress
- Head trauma or a history of traumatic brain injury
- Poor blood glucose control and excessive hypoglycaemia (low blood sugar)
- Pituitary tumours (rare)
Negative effects include FSH suppression (less estrogen), inhibition of progesterone, inhibition of aromatisation (conversion of testosterone to estrogen/increasing androgens and a higher risk of PCOS, excessive body and facial hair growth), early destruction of the corpus luteum (less progesterone).
Low thyroid function or thyroid receptor function
Thyroid hormone has been shown to stimulate progesterone release. Receptors for thyroid hormone are found on the surface of the ovary, and act upon ovarian follicles and reduce thyroid hormone receptor function, leading to decreased follicle numbers.
Research has demonstrated that thyroid hormone helps to regulate growth, cell oxygen consumption, metabolism, embryonic development, tissue differentiation and maturation. Low thyroid has been associated with altered ovarian function, irregular menstrual cycles, reduced fertility and high miscarriage rates. This is a reason why fertility experts and IVF clinics will emphasise the need for optimal levels of thyroid stimulating hormone, and thyroid hormones for fertility and infertility treatments.
Interestingly spikes in thyroid releasing hormone, by a gland called the hypothalamus in the brain, can lead to increases in thyroid stimulating hormone to try and increase thyroid hormone, but may also increase prolactin levels as well.
Nutrient insufficiencies
A number of nutrients can influence progesterone production, some directly and some indirectly.
- Magnesium – Helps to regulate pituitary function and FSH, LH and TSH levels.
- Zinc – Supports FSH levels which can in turn help to support ovulation and supports the utilisation of progesterone.
- Vitamin B6 – Has been shown to increase progesterone levels.
- Vitamin C – Shown to help support levels of progesterone.
- Vitamin E – Shown to support healthy progesterone levels, potentially through its antioxidant effect.
Supporting nutrient status, first by addressing dietary habits, underlying digestive issues, reviewing exercise volume etc is a must. Additional support with supplements may be beneficial in some individuals.
These are a few areas that I would consider, however, everyone can be unique in terms of their physiology and how this might be impacting the end production of hormones like progesterone.
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