Menstrual Cycle Flashcards
What is the Age range of the Menstrual Cycle?
Begins around age 12 and ends around age 50
How many days can a Cycle be? what is the Avg?
21-40 days, AVG = 28
Which phase is most likely to vary?
Follicular Phase
What is the Follicular phase?
single Primary follicle matures, Follicle also ruptures to release oocyte at ovulation.
What is the Luteal Phase?
Remaining follicle becomes Corpus Luteum, Uterine endometrium breaks down –> menstruation.
Which two gonadotropins regulate the menstrual cycle?
FSH and LH.
What is the make up of FSH and LH and where are they secreted from?
Glycoprotein hormones both have a common alpha unit with a unique beta unit. They are secreted by the anterior pituitary.
Which has a longer half life FSH or LH?
FSH (3-4hrs) (LH = 20min)
What does FSH do?
Stimulates granulosa cells
Facilitates estrogen production
stimulates spermatogenesis
How does FSH facilitate estrogen production?
It upregulates aromatase (CYP19)
What does LH do?
Stimulates ovulation.
“LH surge” right before oocyte release.
Testosterone production
Where are the places LH acts to stimulate Testosterone production?
Follicle thecal cells.
Leydig cells in Testes.
What hormone controls the release of FSH and LH? Where is it also released from?
Gonadotropin-releasing Hormone.
Hypothalamus
What are two things the maturing follicle secretes?
Estradiol and Inhibin.
What is the most potent of the natural estrogens?
Estradiol.
What kind of hormone is Inhibin?
Peptide dimer hormone.
What is the result of increased Estradiol and Inhibin? what is the mechanism to obtain the result?
Decreased FSH levels.
Estradiol Suppresses GnRH release.
Inhibin Suppresses FSH release.
What are other actions of Estradiol?
Stimulate endometrial regeneration.
Promotes cervical mucus good for sperm.
What causes LH surge and how?
Estradiol levels >200 pg/ml for >48hr.
High estradiol levels reverse suppression LH release.
Estradiol can act DIRECTLY on pituitary gland.
What produces Progesterone?
Corpus Luteum
What are the main functions of Progesterone?
Prepeare endometrium for implantation of embryo.
Suppresses GnRH release.
What happens when LH Levels drop?
Corpus Luteum degenerates.
Progesterone released from CL –> Menstruation
When are Progesterone levels generally the highest?
During Pregnancy (100-200 ng/ml)
Where is the embryo implanted post fertilization?
Endometrium.
What happens immediately after fertilazation.
The blastocyst (embryo) secretes human chorionic gonadotropin (hCG)
How soon can hCG be detected?
6-8 days post fertilization.
What similarities do hCG and LH have?
They both maintain the corpus luteum.
When does the placenta begin producing progesterone and Estriol (E3)? What is this process refereed to as?
Around 12 weeks after fertilization.
“Luteal-Placental Shift”
Why do progesterone levels continue to rise?
So the fetus can use it to synthesize glucocorticoids and sex steroids.
What is Estriol produced from and when is it most prominent?
Produced from estradiol or estrone and ONLY during pregnancy.
What happens to levels of progesterone just before birth? What are theories of why?
The levels fall dramatically.
Could be signal to induce labor.
Progesterone suppresses contractility.
Progesterone suppresses maternal immune response to fetus.
Inhibits lactation.
How many natural estrogens are there?
3 types (Estrone, Estradiol, Estriol)
What are the characteristics of Estrone?
(E1) It is the most abundence post-menopause. Main sources is FAT.
What are the characteristics of Estradiol?
(E2, 17beta-estradiol)
Most abundant in reproductive women.
Most POTENT
Main source is Ovaries.
What are the characteristics of Estriol?
(E3)
Most abundant estrogen in pregnancy.
Generated from DHEA (most abundant steroid)
Main source is Placenta.
What is common in the synthesis of the estrogens?
They all are derived from other steroids and use CYP19 Aromatase.
If Estriol is produced from either Estrone or Estradiol, where is it produced?
In the liver.
If Estriol is produced directly from 16alpha-OHDHEA where is it produced?
In the Placenta.
What is the mechanism of action for all the Estrogens?
Estrogens bind to the Intracellular Estrogen Receptor (ERalpha) which alters gene transcription.
What tissues do Estrogens primarily target?
Ovaries, Uterus, Breast.
What are the Non-Menstrual effects of estrogen?
Promote development of secondary sex charc.
Decreases bone resorption/increases formation
Lower LDL, Increase HDL, opposes aldosterone
Positive mood, neuroprotection, softer skin, increased liver proteins and coagulation factors.
How many natural Progestogens are there?
Progesterone and 17alpha-hydroxyprogesterone.
Which progestogen is the main one?
Progesterone is the principle circulating one.
Where is progesterone formed?
Corpus luteum and adrenals.
What is the level of progesterone in the luteal phase?
10-15 ng/ml
Where is 17alpha-hydroxyprogesterone formed?
Primarily in the Adrenals.
When are there elevated levels of 17alpha-hydroxyprogesterone.
During pregnancy. In CAH (diagnostic for defective CYP21).
What is the level of 17alpha-hydroxyprogesterone in the luteal phase and the 3rd trimester?
1-5 ng/ml in Luteal
up to 30 ng/ml in 3rd trimester.
What are the two progestogens intermediates for?
Glucocorticoids and mineralcorticoids.
What is the mechanism of action for progestogens?
Progestogens bind to intracellular progesterone receptors (PR) which alters gene transcription.
Does progesterone always bind to a PR?
No, Progesterone can bind to other sites and cause non-transcriptional effects.
What are the primary targets for Progestogens?
Uterus, Breasts.
What are the Non-Menstrual effects of Progestogens?
Progesterone alters sperm motility and may serve as an “attractant” .
Progesterone is likely a “neurosteroid”
What is Dysmenorrhea?
The “crampy” pelvic pain associated with menstruation.
What is the onset of Dysmenorrhea?
Typically 1-3 days before menses. Interferes with normal daily activity. (not just menstrual pain)
What are possible accompanying symptoms of Dysmenorrhea?
Heavy blood loss, nausea, vomiting, headache.
What is Primary Dysmenorrhea?
Thought to be because release of prostaglandins and leukotrienes.
Cause contraction of uterus, tissue hypoxia, pain.
stronger more frequent contractions.
What is Secondary Dysmenorrhea?
Most common cause is endometriosis.
Also uterine polyps, pelvic infections, cervical stenosis.
What is endometriosis?
When growth of endometrial cells outside the uterus.
What is the prevalence of Dysmenorrhea?
Approx. 25% of women, most common in teens and 20’s. In adolescents est. 70-90%.
Childbearing may reduce incidence.
What is the nonpharmacologic treatment of Dysmenorrhea?
Topical heat
Exercise
low-fat/vegetarian diet.
What is the Pharmacologic treatment of Dysmenorrhea?
1) NSAIDS first line.
Begin 1 day prior to onset of menses.
2) Oral contraceptives
decrease endometrial proliferation
3) Depot medroxyprogesterone (MPA) Causes amenorrhea (loss of cycle)
4) Levonorgestrel IUD
Reduces incidence by 50%
Suppresses endometrial proliferation
Amenorrhea in as many of 60%
What is Premenstrual Syndrome (PMS) characterized by?
Mood swings, depression, anxiety, insomnia. appetite changes join/muscle pain headache weight gain/fluid retention breast tenderness, acne
What is the incidence of PMS?
75%
Most common in women age 25-35
Onset 1-2 weeks prior to menses.
What is Premenstrual Dysphoric Disorder (PMDD)?
Severe PMS
Severe depression, hopelessness, irritability.
may be associated w/ psychiatric disorders
3-8% patients w/ PMS
What are 3 categories of treatments for PMS/PMDD?
- Lifestyle changes
- Antidepressants
- Hormonal Treatments.
What lifestyle changes may help PMS/PMDD?
- Decreased caffeine, alcohol, sugar, salt
- Increased exercise.
- Vit. B6 (50-100mg/d), Ca
How can antidepressants help treat PMS/PMDD?
- SSRIs are very effective (1st choice)
given continuously, only during luteal phase, or w/ onset of symptoms. - Tricyclic antidepressants (clomipramine)
- Venlafaxine
What Hormonal treatments can be used for PMS/PMDD?
- GnRH agonists/antagonists.
- Suppress release of FSH/LH, decrease symptoms
- Antiestrogenic effects limit use - Oral/Depot Contraceptives
- Effective by stabilizing hormonal swings
- can cause same effects as luteal phase.