Amenorrhea Flashcards
What are the 3 most common causes of amenorrhea?
1) Hyper-hypo (gonadal dysgenesis)
2) Mullerian Agenesis
3) Congenital AIS
Etiology of MRKH
Activating (gain of fxn) mutation in AMH or AMH-R; association with GALT mutation?
Presentation of MRKH
Normal therlarche and pubarche
Short vagina without symptoms of obstructed menses
Some with skeletal and urologic abnormalities
What percentage of MRKH women have concomitant urologic abnormalities?
15-40%
Imaging of choice for MRKH eval
MRI
Treatment for MRKH
Creation of fxnl vagina (dilators, McIndoe, Vecchieti); gestational carrier
Anatomy of congenital defect in urogenital sinus development
Agenesis of lower vagina
Imperforate hymen
2 etiologies of intrauterine adhesions
Asherman syndrome
TB endometritis
3 categories of anatomic abnormalities leading to amenorrhea
Congenital abnormalities of Mullerian development (MRKH, AIS, 5-alpha reductase def)
Congenital defect in urogenital sinus development
Intrauterine adhesions
3 categories of disorders of HPO axis leading to amenorrhea
Hypothalamic dysfunction
Pituitary dysfunction
Ovarian dysfunction
Pathophysiology of Kallman’s syndrome
Failure of olfactory and GnRH neuronal migration from olfactory placode
Genetics of Kallman’s syndrome
X-linked (most common): Anosmin 1 – males only!
Encoded by KAL1 gene on X chromosome (short arm)
Part of fibronectin family, responsible for cell adhesion and protease inhibition
Autosomal:
Fibroblast growth factor receptor (FGF-1 R/KAL2) – autosomal dominant;
female with amenorrhea/anosmia
Prokinecticin (PROK2) – autosomal recessive; can be normosmic or anosmic
Mechanism of anovulation in anorexia
CRH-mediated opioid suppression of GnRH
Metabolic abnormalities with anorexia
- Decreased: FSH, LH, E2, IGF-1, leptin, T3
- Increased: cortisol, reverse T3, ghrelin, GH, NPY
- Normal: PRL, TSH, T4
3 main categories of hypothalamic dysfunction
Isolated GnRH deficiency (Kallman’s)
Functional hypothalamic amenorrhea (ie eating d/o, stress, excessive exercise)
Brain tumors, cranial radiation, TBI
% of non-functional pituitary tumors that derive from gonadotrophs
80-90%
Pathophys of how gonadotroph tumors affect HPO axis
Stalk compression
- Interrupt GnRH
- Block dopamine –> increase prolactin
LH, FSH, TSH, HCG structure
Common alpha subunit, different beta subunit
Messenger system for GnRH stimulation of LH and FSH production
G protein second messenger, calcium dependent system
Rate limited step in synthesis of LH and FSH
Synthesis of beta subunits of each gonadotropin (prior question: alpha subunits common and secreted with non-functional tumors)
Clinical presentation of gonadotropin adenomas
Markedly supranormal FSH level associated with a subnormal LH concentration
A serum free alpha subunit concentration that is supranormal when intact FSH and LH are not
Markedly elevated serum estradiol concentration and an FSH concentration that is not suppressed, associated with endometrial hyperplasia and polycystic ovaries (a la OHSS); even a “normal” FSH is not appropriate when the estradiol is markedly elevated and the LH suppressed.
Ddx of pituitary dysfunction leading to amenorrhea (4)
Hyperprolactinemia
Pituitary tumors
Empty sella syndrome
Pituitary infarct of apoplexy
Most common chromosomal abnormality in gonadal dysgenesis
Turner syndrome