Intro To PCOS Flashcards
WHY PCOS?
arguable most prev. medical condition in women
What systemic metabolic manifestations are associated with multiple symptomatology? (9)
endocrine, gynaecological, diabetic, dermatological, eating
disorder, psychiatry - complex
- life long impact from IR
-Obesity has bigger impact on PCOS compared to normal esp IR
Polycystic Ovaries (5)
-increased numbers (>20) of small antral follicles (2-9mm)
= dependent on quality : visible on high quality transvaginal u/s transducers (arranged as necklace of pearls)
There is a disorder of follicle growth at all stages:
– Possibly inc. proportion of primordial follicles & inc. no. of activated (primary) follicles
– Arrested antral follicle growth before they mature
– Lower rates of atresia » antral follicles persist (visible on u/s)
-some cases there is a failure of df selection and therefore anovulation infertility
why are they called cysts?
They are arrested follicles not cysts - just named due to their initial discovery but these differ from ovarian cysts.
PCOS discovery (2)
Described as obesity, hirsutism and anovulation in the presence of bilaterally enlarged sclerocystic (hardened) ovaries
(1935) - Stein + Leventhal
Diagnosis then and now (2)
Then: visuall - biopsies, surgeries, deaths (post mortem)
now: ultrasounds +(transvaginal probe)
spectrum of presentation =Lack of consensus for definition
- now measured using rotterdam criteria POST-EXCLUSION of other disorders
disorders that mimic PCOS/ diagnosis of exclusion: (3)
– Non-classical adrenal hyperplasia (most common is deficiency of 21-hydroxylase → ↑17-hydroxyprogesterone & androgens = PCOS Symp’s)
– Hyperprolactinemia, thyroid disease, Cushing’s syndrome
– Ovarian hyperthecosis (very rare) - nests of luteinized theca cells
Rotterdam Criteria : Diagnosis - need 2 out of 3 criteria (6)
-polycystic ovaries
-Hyper-androgenism
-Ovulatory dysfunction
Polycystic Ovaries: (20 or more follicles measuring 2-9mm diameter and/or increased ovarian volume >10ml in either ovary & no DF >10mm)
-Technique and equipment dependent. T/V imaging not always appropriate
Hyper-androgenism: (clinical (acne/ hair)/biochemical evidence) Assays not
standardized across labs; normative data not clearly defined; clinical hyperandrogenism difficult to quantify; ethnicity
Ovulatory Dysfunction: (Oligomenorrhea/anovulation): Frequent bleeding
<21d or infrequent bleeding >35d.
-To confirm ovulation serum progesterone level at mid-luteal phase (d21-22) of cycle (values ≥7ng/ml needed for regular luteal function)
Polycystic ovary morphology (PCOM) (3)
NORMAL: ≤5 follicles in an ovary with a small amount of stroma early follicular mid-follicular ovulation - then DF emerging + shrunk other follciles
ANOVULATORY PCO: ≥ 20 follicles, 2-9mm diameter arranged necklace follicles around enlarged core of dense stroma - ovarian volume >10mls, with NO df
OVULATORY PCO: scan early = anov. , continue scanning during cycle = emergence of DF but instead of others shrinking + dying - they persist
Refinement of Rotterdam criteria - phenotypes (7)
(table)
A: hyperandro., OD, PCOM
B: hyperandro., OD,
C:hyperandro., PCOM
D: OD, PCOM
- Phenotypes A&B are considered classic PCOS → (2/3 of cases) + also common in these phenotypes is BMI and metabolic syndrome
- Phenotype C (ovulatory PCOS) → BMI is often normal, but if BMI increases can alter phenotypic presentation
- Phenotype D (normoandrogenic PCOS) includes chronic anovulation + PCOM but normal serum androgens and no HA
Anovulation (4)
- Most women with PCOM probably have regular/almost regular cycles
- Most women with PCOS and cycle problems have oligomenorrhoea
- Main difference between ov and anov is also the level of IR - IR tps them into Anov
- Adult rhesus macaques fed western style diet (high fat/sugar) & exposed to chronically elevated T from pre-puberty to menopause altered small AF no.’s, morphology and transcriptome
What are the candidates for follicle arrest? (4)
– androgens
– intra-follicular inhibitors eg AMH
– defect in apoptosis (follicles that don’t shrink + die)
– dysregulated gonadotrophin secretion (both FSH and LH)
Prevalence of PCO (9)
PCO present in
– 32% of patients with amenorrhoea
– 87% with oligomenorrhoea
– 87% with hirsutism and regular cycles
– 75% of bulimics?
– 22% of ‘normal’ population
-most common cause of anovulatory infertility-73%
Numerous studies since on prevalence:
– PCOM approx. 20%
– PCOS 5-10% depending on definition
PCOS prevalence across populations (4)
- PCOS presentation in European pop differs from US pop
- US: variability seen between Hispanic , African-American + White pop.’s
- East Asian population w/ PCOS have ↓ BMI + hirsutism compared to other population
- South Asian populations have greater IR ; metabolic sequelae and obesity cf to other populations
Aetiology- genetics (8)
- Familial aggregation
– Sisters more likely to be affected
– first-degree relatives have higher rates of metabolic abnormalities (including insulin resistance, decreased beta-cell function etc)
– Male relatives of women with PCOS increased prevalence of metabolic syndrome & obesity compared to general US male population - Monozygotic twins twice as likely to both have PCOS than
dizygotic. - common finding of raised androgen led to belief that PCOS is caused by an inherited disorder -most likely in the steroid biosynthetic pathway
- Many candidate genes were investigated: all ‘obvious’ ones ruled out
- Complex polygenic disease – involves subtle interaction with environmental factors (intra- & extra-uterine)
The Chinese Studies (4)
- 1st Genome-wide association study (GWAS) identified causative
genes in Han Chinese women (2011)
– 744 women with PCOS & 895 controls - 3 loci linked and candidate genes within these loci are: (Important in aetiology of PCOS regardless of ethnicity)
– LHCGR
– FSHR
– THADA…linked to T2D
– DENND1A …linked with obesity - (October 2014) GWAS confirmed variants in DENND1A, THADA, FSHR &
INSR were associated w/ PCOS in Europeans - Confirming the biological relevance of PCOS-associated variants by molecular analysis (e.g. expression analysis, targeted genetic disruption in cell culture or organism) is critical to confirming findings from GWAS – rarely done.
Forced expression of DENND1A.V2 in normal theca cells results in
augmented androgen and progestin production (3)
- Theca cells were transfected with DENND1A isoform and treated
with/without forskolin (to stimulate cAMP) - Measured production of various androgens and progestegins
= DENND1A.V2 overexpression recreated(recapitulated) hyperandrogenic theca cell function (that women w/xs androgen gene have)
PCOS & Gonadotrophins I - LH:FSH(6)
Consistent feature of PCOS is disordered gonadotrophin sec. = downstream ovarian consequences:
– Elevated/upper-normal mean LH
– Low/low-normal FSH
(basically generally see an altered ration of LH:FSH)
– Rapid GnRH frequency → favouring rapid LH pulse secretion
study: 24h LH pulse profiles from control lean and obese women (blue) and lean and obese PCOS women (red).
= Clearly showing increased LH measurements that reflect an increase in LH pulse frequency & amplitude irrespective of body weight (=inherent)
Why does dysregulated gonadotrophin secretion occur? (4)
Impaired negative regulation of GnRH pulse generator because: High T impairs -ve feedback by Proges. in presence of E2
– Proof: block Ar with flutamide → proges. then able to↓ LH & FSH (reinstate function)
– Also see that in late puberty girls without HA respond to proges. w/↓LH pulse frequency overnight, which did not occur in HA girls at same pubertal stage
LH levels in PCOS- graph result
The higher LH will drive thecal cell hyperplasia and the hyper-androgenemia, but HA is also intrinsic and can be independent of LH.
Increased androgens in PCOS (5)
– Most consistent biochemical abnormality w/PCOS: hypersecretion of androgens
– ideal to measure free (T) i.e. SHBG and total testosterone to work out free T
– anov> ov>normal
– increased androgen production by the ovary, even in ovPCO
– Increased LH leads to increased androgen production
Clinical HA signs (2)
– Androgenic alopecia, hirsutism (excess terminal hair) & acne
– consistently reported as most distressing symptoms in
women
testosterone levels & symptoms (6)
normal: 0.5-2.0nmol/L
PCO: higher
Anov: even higher
Anov H: even higher than higher
= increasing T w/ increasing severity of symptoms
≥ 7nmol/L then need to screen for androgen-producing tumour
Explain the MoA of Androgens + hirsutism (4)
- Testosterone converted to DHT at hair follicle
- DHT more potent androgen
- 5a-reductase may be higher in PCOS
- Not just absolute levels of testosterone but the sensitivity to AR – see this with acne
Where is all of this excess androgen coming from? - and how do you test it? (3)
In women with PCOS – main source of androgens is from the ovary(theca cells) + adrenal gland
Test w/ Dexamethasone: suppress adrenal gland ,still high androgens = coming from ovary, if reduced = adrenal gland
in women w/ PCOS: main source = OVARY
diagram
steroid production by theca (6)
Measuring Adione + proges. levels - normal vs PCOS: both had higher levels w/PCOS
look at these because its the same pathway (all levels of androgens are higher in theca) = Intrinsic dysfunction in theca cells (CYP17):
* Stable phenotype of PCOS theca
* CYP17 promoter is more active
* CYP17 mRNA degrades more slowly
Oestradiol in PCOS?
There is not a big increase, assumed because there is no increase in aromatase + levels of androgen r’s are not upreg. = no binding.
Due to ↑in number of arrested follicles will see a slight ↑E2 but not DF levels
in spite of ↑T – why? (2)
- Levels of AR may not be increased in GC, hence cannot bind excess T
- No massive increase in aromatase levels
what is Insulin is co-gonadotrophin with and what is the triple whammy? Also explain secondary PCOS due to T1D. (5)
LH
1) women w/ PCOS have hyper-androgenemia because of inherent problem of making xs androgens
2) also have xs androgen because of high LH
3)Hyperinsulinemia will also augement hyper-androgenemia via cross talk on pathways
Women with T1D have to take exogenous insulin → often develop HI → leads to HA → develop secondary PCOS
What causes the change in morphology in PCOS?
Increased follicle activation and recruitment but growth of follicles arrested before they mature
Morphology Studies explained - 3 studies (11)
- Hughesden 1982:
– counted follicle numbers in sections from 17 PCOs and 17 normal ovaries
– found 2x all of the growing stages in PCO - Webber et al (2003)..Lancet
– counted follicles in biopsies
– 6X more primary follicles in PCOS
– no significant increase in primordials - Maciel GA et al, (2004)…JCEM
– Counted follicles in sections
– ‘stockpiling’ of primary follicles in PCOS
Increased follicle activation and recruitment but growth of follicles arrested before they mature
What might cause increased numbers of follicles? (9)
- Androgens seem likely candidate for increasing follicle numbers early in folliculogenesis:
– Androgens involved in stimulating primordial follicle initiation and increasing
number of small antral follicles
– LH hypersecretion amplifies androgen production by theca
– AR expression found in GC at all follicle stages - Increased numbers at the primary stage persist to antral stages?
— Low/normal FSH:LH ratio reduce normal maturation
— Lower rate of atresia - Intra-ovarian factors involving follicular recruitment & growth also contribute
― AMH & others TGF-β superfamily members
― AMH production high from granulosa cells of PCO(Pellat et al (2009) JCEM)
― Reflected in AMH serum levels which 2-3x higher in PCO cf normal
Excess foetal T (exposure of female animals to elevated
androgens in utero studies): (4)
induces PCOS-like traits that manifest in offspring during adulthood:
– Sheep models had increased LH pulsatility and impaired E2/P feedback
– Offspring of T-exposed monkey mothers after puberty →
» LH hypersecretion, ovulatory dysfunction, hyper-androgenism and IR
» 50% have enlarged ovaries and increased follicles counts
– Adolescent girls with HA have similar pattern of rapid LH pulse secretion before menarche
– Obesity in pubertal girls also alters LH pulses
– Pregnant women with PCOS? Maternal T is raised but is foetus
exposed?
» High levels of SHBG & aromatase activity in placenta, prevent maternal T crossing over, so a female foetus is not androgenised
» Maybe excess secretion coming from foetus itself?
Androgens & Hypothesis of PCOS origin - AMH in-utero (7)
Exposure of developing hypo. to XS androgen before final programming of steroid feedback + other regulatory mechanisms alters GnRH pulsatility + feedback
- XS AMH in utero may affect development of female foetus
- This AMH arises from mother and not the foetus
- In women with normal fertility AMH levels would drop during pregnancy
- In pregnant women with PCOS AMH levels are elevated
Proof: Treated pregnant mice with AMH → altered neuroendocrine phenotype (affects GnRH neurones) of female offspring and induced PCOS-like phenotype
PCO - summary (5)
- Polycystic ovaries are genetically acquired + may have a foetal origin
- There is a defect in the way follicles grow
- There is a basic defect in steroid metabolism
- The gene/s causing this are becoming known
- Endocrine disturbances result in miscarriage, anovulation, infertility and hyper-androgenism
