Hormonal treatment in Nonmalignant Gynaecological Conditions Flashcards
What is the only situation where you use only oestrogen therapy?
For HRT in women that have undergone hysterecomy.
This is because oestrogen alone = Causes proliferation of uterine endometrium/endometrial hyperplasia. And irregular menstrual bleeding in premenopausal women
Describe the three types of oestrogen, describe their potency and there production prior to menopause
Most potent = E2 = Produced in ovaries
Second potent = E1 = Derviced from aromatisation of androstenedione from adrenal glands and ovaries
Least potent = E3 = Not from ovary, instead from irreversible metabolism of E1
Describe the three types of oestrogen, describe their potency and there production after the menopause
After menopause E1 becomes most potent oestrogen = Because ovarian secretion of oestrogens cease.
Instead the remaining production of E2 and E1 comes from peripheral aromatisation of circulating androstenedione in adipose tissue
Describe the different types of oestrogen receptor and where it is expressed
Alpha + beta oestrogen receptors
Alpha = Endometrium, bone, breast cancer cells, ovarian stroma cells, hypothalamus
Beta = Kidney, Brain, Bone, Heart, Lungs, intestines, prostate, endothelial cells
Which oestrogen receptor mainly regulates oestrogens actions of the skeleton/bone
Alpha
Which oestrogens bind more to which receptor
They can all bind to everyone one, But
E2 = Binds to both alpha and beta equally
E1 + Raloxifene = Prefers alpha (better for bone)
E3 + Genistein = Prefers beta
Describe the metabolism and excretion of estrogens
Primarily done in liver
Phase 1 = Hydroxylation by cytochrome p450.
Phase 2 = Conjugation by glucuronyl transferases + Sulphotransferases.
E2 overall is rapidly cleared and only has a half life of 1.7hrs in circulation
BUT it lasts longer generally = Since it can be converted to E1 that acts also = And the oestrogen conjugates are excreted in bile and undergo
enetrohepatic recirculation
Half life or E1 = 4 times longer.
How does SHBG levels effect the physiological effect of oestrogens. What increases/decreases SHBG levels
E2 that is bound to SHBG = Is not biologically active.
Throxine + E2 = Promotes SHBG meaning less overall activity
Androgens, insulin, corticoids, progesterons, and GH = Suppress SHBG production, meaning more overall activity
How come oestrogens can be taken orally and still get absorbed and make it through first pass hepatic metabolism?
Normal oestrogens would bascially be all gone from hepatic metabolism
Ethinyl oestradiol = The addition of an ethinyl group prevents its inactivation and promotes absorption.
Talk to me about SERMS
They bind to oestrogen receptors, having some agonist effects in some areas and antagonistic effects in other areas
Describe 3 SERMs, their uses, their areas of action.
Clomiphene = First one discovered. Used in PCOS and ovulation infuction. Centrally blocks negative feedback of oestrogen, so you get a FSH and LH surge. Shown that it also slows bone loss if opphorectomised rats
Tamoxifen = Oestrogen antagonist at the breast, but agonist in skeleton and cardiovascular system. But it does cause endometrial hyperplasia +/- adenocarcinoma. (so also acts in uterus)
Raloxifene = Inhibits bone mineral density loss, but does not stimulate endometrium, and is antagonist at breast. So does not increase risk of breast/endometrial cancer. But helps bones.
What areas of body produce endogenous progesterone? Outside of pregnany what is the biggest source of progesterone endogenously?
Largest source outside pregnancy = Corpus luteum
Other production areas = Adrenal cortex + glial cells in CNS produce small amounts.
What effects does progesteron have on an oestrogen primed endometrium, and what effects on oestrogens
Overall progesterones have an anti-oestrogen effect
Progesterones downregulate E2 receptors by reducing synthesis.
They promote differentiation of glands/stroma and decidualisation
Progesterones also stimulate IGF-1
And stimulation 17-hydroxysteroid dehydrogenase production = Which converts E2 to weaker E1 sulphate version.
This induces endometrial sloughing and uterine bleeding
Talk to me about metabolism and excretion of progesterones
Hepatic metabolism
Metabolised to pregnanetriols and preganediols which are also conjugated with glucoronides and sulphates (like oestrogens)
Then metabolites excreted in bile, with LITTLE enterohepatic recirulcation
Talk to me about how progesterones can be given orally, including the 2 main types
The natural ones cannot be given orally as they are just metabolised by microrganisms and digested
Natural ones can be used transvaginally or transrectally however
But for oral = Need to use synthetic preperations. There are 2 types
1) 21 carbon steroids derived from 17alpha hydroxyprogesterone
2) 19 carbon steroids derived from nortestosterone