Polycystic ovary syndrome (PCOS): diagnosis and metabolic screening

• Off combined oestrogen-progestogen contraception for at least 3 months; at the start of the follicular phase if cycles are preserved.

Laboratory tests (in the morning, before 8 am for 17-hydroxyprogesterone)

• Total testosterone (by mass spectrometry if possible)
• SHBG (to calculate the free androgen index)
• 17-hydroxyprogesterone (in the morning, at the start of the follicular phase)
• Serum prolactin
• TSH
• β-hCG (if amenorrhoea)if needednon-French guidelineAmenorrhoea (rather than oligomenorrhoea): exclude pregnancy ^[2].
• FSH and oestradiol (if amenorrhoea)if needednon-French guidelineAmenorrhoea: raised FSH and low oestradiol point to premature ovarian insufficiency; low or low-normal LH and FSH with low oestradiol point to hypothalamic amenorrhoea ^[2].
• Progesterone in the middle of the luteal phase (if cycles are regular, to confirm anovulation)if needednon-French guidelineHyperandrogenism with regular cycles, when the diagnosis depends on ovulatory dysfunction: the 2023 international guideline and its US synthesis propose measuring progesterone to confirm anovulation ^[1,3]. The sample is taken in the mid-luteal phase, on day 21 of a 28-day cycle ^[4].
• Delta-4-androstenedione (if testosterone normal)if needednon-French guidelineNormal total and free testosterone while hyperandrogenism is still suspected: can be measured, bearing in mind its lower specificity ^[1].
• DHEA-S (if testosterone normal, or suspected adrenal cause)if needednon-French guidelineNormal total and free testosterone: lower specificity and decline with age ^[1]; virilisation or rapid progression: very high levels in favour of a secreting tumour ^[2].
• AMH (adult, instead of ultrasound for ovarian morphology)if needednon-French guidelineAdult in whom only one of the other two criteria is present (irregular cycles or hyperandrogenism): AMH can replace ultrasound to define polycystic morphology; never alone, never together with ultrasound, not in adolescents ^[1].
• 24-hour urinary free cortisol (if signs of hypercortisolism)if needednon-French guidelineMany signs of hypercortisolism, especially the most discriminating ones (proximal muscle wasting, facial plethora, purple striae, easy bruising): screen for Cushing's syndrome with 24-hour urinary free cortisol, late-night salivary cortisol or the overnight dexamethasone suppression test ^[2].

Fasting laboratory tests

• 75 g oral glucose tolerance test (fasting and 2-hour glucose)
• Lipid profile
• Fasting plasma glucose (if the OGTT is not possible)if needednon-French guidelineOGTT impossible or refused: fasting plasma glucose and/or HbA1c, markedly less accurate ^[1].
• HbA1c (if the OGTT is not possible)if needednon-French guidelineOGTT impossible or refused: alternative of lower accuracy ^[1,2].

Every 1 to 3 years depending on risk factors

• 75 g oral glucose tolerance test (or fasting plasma glucose if not possible)
• Lipid profile (depending on the presence of dyslipidaemia and cardiovascular risk)if needednon-French guidelineAfter the initial tests, the frequency of lipid tests depends on hyperlipidaemia and other risk factors or on overall cardiovascular risk ^[1].

Pregnancy plan or request for assisted reproduction

• 75 g oral glucose tolerance test