PCOS Flashcards
def PCOS
characterised by oligomenorrhoea/amenorrhoea and hyperandrogenism (clinical/biochemical), adn multiple cysts in the ovary on US which represent arrested follicular development in absence of other causes (eg later-onset adrenal hyperplasia/cushings)
frequently associated with obesity, hyperinsulinemia, insulin resistance, type 2 DM and dyslipidaemia, hypertension, hyperlipidaemia and increased CVD
mechanisms may play a role in macrovascular disease in women
aetiology PCOS
env factors - related to diet and the development of obesity
genetic variants - genes relating to gonadotrophin, insulin and androgen synthesis, secretion and action, weight and energy regulation - may influence the development of PCOS
hyperinsulinaemia results in increased ovarian androgen synthesis and reduced hepatic SHBG (sex hormone binding globulin) synthesis = increased free androgens
epi pcos
most common cause of infertility in women
affects 6-8% of women
sx pcos
menstrual irreg - oligomenorrhoea/amenorrhoea - cycles take longer than 35 days or fewer than 10 cycles a year
dysfunctional uterine bleeding, infertility
symptoms of hyperandrogenism - hirsuitism, male-pattern hair loss, acne - usually beginning shortly after menarche (first menstrual cycle)
acanthosis nigricans (sign of severe insulin resistance) - velvety thickening and hyperpigmentation of the skin or axillae or neck
sometimes associated with marked obesity, but weight may be normal
mild virilisation occurs in severe cases
subfertility
criteria for pcos dx
2 of the following three criteria are present and other ddx have been excluded (androgen secreting tumour, cushings syndrome, congenital adrenal hyperplasia)
- menstrual irregularity (amenorrhoea or oligomenorrhoea) due to oligo- and/or anovulation
- clinical (hirsuitism, acne, frontal balding) or biochemical evidence of hyperandrogenism
- polycystic ovaries (multiple cysts) on US examination
signs pcos
hypertension
acanthosis nigricans on neck and skin flexures - represents hyperinsulinaemia
ic pcos
sex hormones
serum prolactin is slightly elevated in PCOS but values more than 1.5-2 tumes upper limit of normal suggest pit/hypothalamic disease
serum 17- hydroxyprogesterone is elevated in patients with non-classic congenital hyperplasia
transvaginal US = good visualisation of the ovaries - 12 or more follicles in each ovary, measuring 2-9mm and/or increased ovarian volume >10mL
blood
tests to exclude hyperprolactinaemia, hypo/hyperthyroidism (thyropid function tests), congenital adrenal hyperplasia (17OH-progesterone) and cushings syndrome (if clinically suspected)
look for impaired glucose tolerance/T2DM - fasting glucose, HbA1c (oral glucose tolerance test if either is abnormal)
fasting lipid profile
Other causes of irregular cycles should be excluded before the diagnosis is made if there is clinical suspicion eg thyroid dysfunction, hyperprolactinaemia, congenital adrenal hyperplasia, androgen secreting tumours, and Cushing’s syndrome
sex hormones pcos
serum total testosterone conc may be normal in PCOS and fail to detect biochemical hyperandrogenism - because SHBG is suppressed = raised free testosterone (bioavailable)
biochem evidence of hyperandrogenism is demonstrated by raised free androx index (serum total testosterone/sex hormone binding globulin conc) - this is a measure of bioavailable testosterone
total testosterone concentrations more than 1.5-2x upper norm or a history of rapid virilisation are likely to be associated with an androgen secreting tumour of teh ovaries/adrenal gland
If clinically hyperandrogenic and total testosterone >5nmol/L check 17-hydroxyprogesterone and exclude androgen secreting tumours. LH is raised in 40%, testosterone in 30%.
blood pcos
increase in LH, LH:FSH ration (>3), testosterone, androstenedione and DHEA-S
reduction in SHBG
