Pregnancy - Endocrine Changes Flashcards
Pregnancy and Progesterone
Progesterone
during the first 2 weeks stimulates the fallopian tubes to secrete the nutrients the zygote/blastocyst requires
placenta starts production at 6 weeks and takes over at 12 weeks
progesterone inhibits uterine contractions by
1. Inhibiting production of prostaglandins
2. Decreasing sensitivity to oxytocin
stimulates development of lobules and alveoli
Pregnancy and Oestrogen
Oestrogen
oestriol is major oestrogen (not oestradiol)
stimulates the continued growth of the myometrium
stimulates the growth of the ductal system of the breasts
Pregnancy and Prolactin
Prolactin
increase during pregnancy probably due to oestrogen rise
initiates and maintains milk secretion of the mammary gland
essential for the expression of the mammotropic effects of oestrogen and progesterone
oestrogen and progesterone directly antagonises the stimulating effects of prolactin on milk synthesis
Pregnancy and hCG
hCG
secreted by syncitiotrophoblast, stimulated by GnRH produced in adjacent cytotrophoblast
can be detected within 9 days, peak secretion at 9 weeks
mimics LH, thus rescuing the corpus luteum from degenerating and ensuring early oestrogen and progesterone secretion
stimulates production of relaxin
may inhibit contractions induced by oxytocin
Pregnancy and Other Hormones
Also
Relaxin: suppresses myometrial contractions and relaxes the pelvic ligaments and pubic symphysis
hPL: has lactogenic actions (insignificant with respect to prolactin) - antagonises insulin, therefore making less glucose available to the mother - enhances protein metabolism
Pregnancy Hormones - Example Question
A 42-year-old woman was seen in Endocrinology Clinic with a 4 month history of amenorrhoea. On questioning she reports having to wax her arms and upper lip. Her mother went through early menopause at 28 after having an emergency hysterectomy post-partum. On examination her BMI is 38 but otherwise unremarkable.
Her GP has kindly ordered blood tests prior to her appointment
Investigations
LH 40 IU/L (5 to 25 IU/L) FSH 8 IU/ (1 to 11 IU/L) Estradiol 720 pmol/L (70-500 pmol/L) Progesterone 220 nmol/L (35-92 nmol/L) Thyroid Stimulating Hormone 5.6 mIU/L (0.5 -6.0 mIU/L) Prolactin 700 mIU/L (105-548mIU/L)
What is the most likely diagnosis?
Prolactinoma Polycystic Ovarian Syndrome Premature Ovarian Failure > Pregnancy Subclinical Hypothyroidism
The most likely diagnosis is pregnancy. The elevated estrodiol and progesterone is characteristic with a slight rise in the LH level.
The prolactin level is only mildly elevated so a prolactinoma is unlikely especially with the rise is other hormone levels. Polycystic ovarian ayndrome is associated with androgen excess and an elevated LH to FSH ratio. While androgen (testosterone) hasnt been measured, it is not associated with rises in estradiol or progesterone.
Premature Ovarian Failure typically presents with low levels of estradiol and a raised FSH level. Subclinical Hypothyroidism is linked with oligoovulation but in this case the TSH level is normal excluding this as a diagnosis
Interpreting FSH, LH, Progesterone
Pregnancy:
- Elevated Estradiol + Progesterone
- Slight rise in LH
- Slight rise in Prolactin
Prolactinoma:
- Markedly raised Prolactin
PCOS:
- Androgen excess i.e. High testosterone
- Elevated LH:FSH ratio
- No increase in estradiol or progesterone
Premature Ovarian Failure
- Low levels estradiol or progesterone
- Raised FSH