About the ads

  1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Can someone explain why a single dose of hCG causes a LH surge?

Discussion in 'Step I' started by auburnO5, Apr 3, 2012.

  1. This forum made possible through the generous support of SDN members, donors and sponsors. Thank you.
  1. auburnO5

    auburnO5

    Joined:
    Dec 15, 2008
    Messages:
    1,360
    Status:
    Medical Student
    SDN 5+ Year Member

    SDN Members don't see this ad. (About Ads)
    I understand that it's made early by the embryo and then syncytiotrophoblasts to keep the corpus luteum producing progesterone.

    I guess I can't figure out why it would cause an LH surge.

    This is in the setting of an anovulatory/infertile female seeking fertility treatment, after doses of menotropins (GnRH?) were given.
  2. lakerfan38

    lakerfan38

    Joined:
    May 26, 2009
    Messages:
    85
    SDN 2+ Year Member
    hCG is very similar to LH.

    Same alpha subunit as LH and similar beta subuint

  3. lookmanohands

    lookmanohands

    Joined:
    Mar 25, 2012
    Messages:
    30
    (here's what I think/remember): The infertile woman is probably lacking FSH and LH. The menotropins are probably acting like FSH to handle what FSH was supposed to do.

    FSH, LH, TSH, and hCG share a common alpha subunit so hCG can simulate an LH surge if you spike it into her. I think it's actually replacing the LH surge, not causing an LH surge
  4. medstud87

    medstud87

    Joined:
    Mar 6, 2011
    Messages:
    111
    Status:
    Medical Student
    SDN 2+ Year Member
    ^This. Basically hCG = LH w/ weak FSH and TSH (TSH can cross placenta--> maternal hyperthyroidism but unapparent because of estrogen increasing TBG). Produced by placenta in order to 'save' the corpus luteum --> production of estrogen/PROGESTERONE from ovaries and corpus luteum until 2nd trimester when placenta takes over. Is actually highest in concentration 2nd and 3rd trimester.

    Key board style question I got from Kaplan... "When can ovaries be removed during pregnancy (I don't know why you'd want to remove them but whatever)?"
    Ans: After 1st trimester because placenta takes over.

Share This Page


About the ads