Respiratory rate, heart rate, blood pressure, and body temperature are the four vital signs of human health. For women, we have a fifth vital sign: the menstrual cycle. The menstrual cycle has been added as a fifth vital sign as it is an essential indicator of health status; the hormones produced throughout the menstrual cycle can affect every body system. This article will walk through the menstrual cycle, discussing the menstrual cycle, including the different phases and testing and treatments that can support each phase.

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What is The Menstrual Cycle?

The menstrual cycle is a monthly cycle that women's bodies go through in preparation for a pregnancy. The menstrual cycle occurs due to communication between the brain and the ovaries. Healthy cycles typically last anywhere from 21-35.

Menstrual Cycle Phases

The menstrual cycle can be broken into three phases: follicular, ovulatory, and luteal.

The Follicular Phase

The follicular phase of the menstrual cycle begins on the first day of menstruation, called day one. Menstruation is the shedding of the uterine lining and produces a bloody discharge. During this time, estradiol and progesterone, our two primary female hormones, are not being made, and thus levels are low. What is being produced is Follicle Stimulating Hormone (FSH). FSH is released from the pituitary gland in the brain and goes to the ovaries. FSH stimulates follicles in the ovaries, which hold eggs, causing them to grow. Between days five and seven, one of the follicles will become the dominant follicle, causing the other to dissolve. The dominant follicle will then produce estradiol, causing the cessation of menstruation. The uterine lining begins to grow again in preparation for a fertilized egg due to estradiol levels, which continue to rise due to continued FSH release. Eventually, estradiol levels will peak, causing the release of another pituitary hormone called Luteinizing Hormone (LH) to be released. This marks the end of the follicular phase and the beginning of the ovulatory phase.

Ovulation

The ovulatory phase lasts from 16 hours to 32 hours. LH stimulation causes the follicle to grow until it ruptures, releasing the egg; the release of the egg is also called “ovulation”. Ovulation is the purpose, or the main event, of the menstrual cycle.

Luteal Phase

The luteal phase begins after ovulation and lasts for 14 days. The leftover follicle remnants turn into a structure called the corpus luteum. The corpus luteum produces the hormone progesterone. Progesterone enhances the function of the uterine lining, ensuring proper blood flow, and thus, nutrients get to it. If the egg is not fertilized by sperm, the corpus luteum will begin to break down, and progesterone levels will begin to fall. Estradiol levels are also falling at this time. Once these hormones are low enough, menstruation will begin, and the entire cycle will repeat itself.

Functional Medicine Labs For Each Section of the Menstrual Cycle

Menstrual cycle testing can be complex to understand and difficult to know how to implement. All hormones involved in the menstrual cycle and all the hormone fluctuations can make it challenging to determine what type of testing is indicated or necessary for you or your patient. While these hormones can be checked at any time in the cycle, their interpretation will depend on when you test them. Let’s break down hormone testing by the menstrual cycle's different phases, including what tests are most important during that phase and what they indicate.

Follicular Phase Testing

FSH

FSH testing, such as the test offered by Access Medical Laboratories, can be done between days two to three of the menstrual cycle. Testing during this time can give insight into the ovarian reserve, or how many eggs are left and or how they are functioning.

Reference range: 5-20 mIU/L

Estradiol

Estradiol testing, such as the test offered by BioReference Laboratories, can also be done during days two to three of the menstrual cycle. When tested at this time of the cycle, levels are used to assess ovarian reserve.

Reference Range: 20-400 pg/mL

Ovulation Phase Testing

LH

LH can be measured in the blood, such as the test offered by ZRT Laboratories. As discussed above, LH begins to be released just before ovulation and is what triggers ovulation. Checking levels mid-cycle can help to determine if ovulation will occur.

Midcycle Peak: 0.61 to 16.3 IU/mL

Estradiol

It may also be important to check estradiol levels mid-cycle, as high estradiol levels at this time can block ovulation.

Midcycle Peak: 150-750 pg/mL

Luteal Phase Testing

Progesterone

Serum progesterone tests, such as the test offered by Boston Heart Diagnostics, should be done in the luteal phase only, as that is the only time progesterone is made. This test should be done 5-7 days after ovulation; for most women, that's between cycle days 19-22. However, as cycles can vary, some practitioners may advise their patients to record the basal body temperature throughout the month, as a rise in basal body temperature is indicative of ovulation, and base testing off of that. Lack of progesterone indicates anovulation, meaning ovulation did not occur.

Reference range: 5-20 ng/mL

Estradiol

Estradiol levels can also be checked during the luteal phase of the cycle. High levels of estradiol in the luteal phase can lead to low progesterone levels as high estradiol blocks progesterone synthesis.

Reference range: 30-450 pg/mL

DUTCH Complete

The DUTCH Complete test is a urine metabolite test that is done during the luteal phase of the cycle as progesterone levels are being assessed. However, this test also shows estrogen levels, androgens including DHEA and testosterone, as well as stress markers, organic acids, and more. This test is popular amongst functional medicine practitioners as it is comprehensive, but also due to the methodology; urine testing shows hormone metabolites, giving insight into how the patient’s body breaks hormones down. This can be especially important for estrogen metabolism, as it is a rather extensive process. A slowdown in any of the three steps in estrogen metabolism can cause a backup of estrogen in the body, leading to a hormonal imbalance.

DUTCH Cycle Mapping

If assessing estrogen or progesterone levels during one time of the cycle isn’t enough, the DUTCH Cycle Mapping test may be the answer. This is an urine test done during one cycle, having women collect urine samples every 1-2 days, allowing for the tracking of both progesterone and estrogens throughout the entire cycle. This can be important, especially for those women with irregular periods, as they may not fit the typical designated days of the stages of a normal menstrual cycle, and thus one-day testing may provide false levels.

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Functional Medicine Treatment for Each Section of the Menstrual Cycle

Phytoestrogens

Phytoestrogens are extracts from botanicals that have estrogenic properties. Examples of phytoestrogens include Hops, Red Clover, and Black Cohosh. Phytoestrogens can be helpful when estrogen levels are lower than they should be due to various reasons, such as in menopause, pituitary and ovarian damage, and more. Because of their effects on estrogens, phytoestrogens can directly help the follicular and luteal phases.

Follicular and Luteal Phase Support: Inositol

Inositols are molecules that our bodies make and are also found dietarily in grains, nuts, and seeds. There are two main types of inositol: Myo-inositol and d-chiro-inositol, both may aid in healthy ovarian functioning, including inducing ovulation.

Ovulation Phase Support: Chaste Tree Berry

Vitex Agnus castus, commonly known as chaste tree berry, is a botanical that has been traditionally used for women’s health. Low doses of Chaste Tree Berry have been found to increase progesterone levels while decreasing estradiol and prolactin.

Luteal Phase Support: DIM

3,3’-diinolylmethane, commonly referred to as DIM, can aid in healthy estrogen levels. DIM functions to aid in phase I of estrogen metabolism, helping to get estrogen out of the body properly. High levels of estradiol can be linked to dysfunctions within estrogen metabolism, and thus DIM can be helpful in these scenarios.

*Note:It’s important to note that although we discussed the above supplements acting on certain parts of the menstrual cycle, the parts of the menstrual cycle are not isolated, and all sections will affect each other.

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Summary

The menstrual cycle is an essential part of every woman's health. Understanding the menstrual cycle, including knowing what happens during each section, can help the practitioner and patient to figure out what type of testing is appropriate and when the testing is warranted. Proper testing and evaluation will then help determine the proper treatment plan, which may include supplements.