Placental Hormones Flashcards
(29 cards)
Referred as the pregnancy hormone.
Human Chorionic Gonadotropin (HCG)
HCG is almost exclusively produced by the _______.
Syncitiotrophoblast
Normal amount of HCG in men and non-pregnant women.
0-5 mIU/mL
What is being detected in the urine to indicate pregnancy?
HCG
Day when the HCG can be detectable in the plasma of a pregnant woman.
7-9 days
High level of HCG can be an indication of
○ multiple fetuses (i.e. twin pregnancy) ○ single erythroblastotic fetus ○ H. mole ○ choriocarcinoma ○ a fetus with Down syndrome
Low level of HCG can be indicative of
○ ectopic pregnancy
○ spontaneous abortion
Where is HnRH produced?
Cytotrophoblast
— which acts on syncytiotrophoblast→ stimulate hCG secretion
What is the metabolic clearance of HCG? ml/l per min/day
3ml/min or 4 liters of plasma/day
Reviewer:
Enumerate the biological functions of HCG:
- Rescue and maintenance of corpus luteum in
early pregnancy→ continued progesterone
production - Downregulation of hCG/LH receptors in corpus luteum when trophoblasts produce sufficient progesterone for pregnancy maintenance
- Stimulates fetal testicular testosterone
secretion and promote male sexual differentiation - Stimulates the maternal thyroid via LH/hCG receptors and TSH receptors.
- Promotes relaxin secretion by the corpus
luteum - Promote uterine vascular vasodilation and
myometrial smooth muscle relaxation - Induces ovulation in the FSH primed ovaries of
non-pregnant women
This relaxes uterus to avoid hyperactivity during pregnancy.
Relaxin
HPL is alson known as
chorionic growth hormone,
chorionic somatomammotropin
At 5-10 days after fertilization, HPL can be seen in the
placenta
During 5th week of pregnancy, HPL can be seen in
serum of pregnant women
It functions as a fail-safe mechanism to ensure
nutrient supply to fetus in times of maternal
starvation
HPL
Acetate and cholesterol is converted to androstenedione in the
Theca cells
Adrostenedione is converted to estrone then to estradiol 17B in the
Granulosa cell
Precursors for Estrogen Synthesis:
○ Maternal plasma dehydroepiandrosterone sulfate (DHEAS) ○ Liver: 16-hydroxy dehydroepiandrosterone ○ Fetal DHEAS
Non-pregnant women ratio of estradiol and estrone to estriol vs during pregnance
Non-pregnant - 1
During pregnancy - 10
What is the principal precursor for fetal steroidogenesis?
Fetal plasma cholesterol
Sources:
20% - maternal transfer
80% - de novo synthesis by fetal liver
This fetal induced modification of estrogen production is due to the inability to convert dehydroepiandrosterone to estradiol.
Placental aromatase deficiency
Disease caused by diminished availability of C- 19 steroid precursor because of the absence of adrenal cortex
Fetal Anencephaly
What happens with the placental estrogen on fetal death or ligation of the umbilical cord?
Marked decrease in placental estrogens -
precursor of placental estrogen is lost
T/F
Estriol is not used anymore to assess the fetal well-being
True
