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Polycystic ovary syndrome - Management
What investigations should I perform?

  • Measure the following to help diagnose polycystic ovary syndrome (PCOS).
    • Total testosterone — this is normal to moderately elevated in women with PCOS.
      • If the testosterone level is greater than 5 nanomol/L, test for 17-hydroxyprogesterone and seek specialist advice.
    • Sex hormone-binding globulin — this is normal to low in women with PCOS. It provides a surrogate measurement of the degree of hyperinsulinaemia.
  • Calculate the free androgen index (the normal range is usually less than 5, but this depends on local laboratories) — this is normal or elevated in women with PCOS. It provides an assessment of the amount of physiologically active testosterone present.
    • To calculate the free androgen index, divide the total testosterone value (in nanomol/L x 100) by the sex hormone-binding globulin value (in nanomol/L).
  • Measure the following to rule out other causes of oligomenorrhoea and amenorrhoea (such as premature ovarian failure, hypothyroidism, and hyperprolactinaemia):
    • Luteinizing hormone and follicle-stimulating hormone — may be increased in women with premature ovarian failure and decreased in women with hypogonadotropic hypogonadism.
    • Prolactin (normal range is less than 500 mU/L) — may be mildly elevated in women with PCOS.
    • Thyroid-stimulating hormone (normal range 0.4–4.5 mU/L).
  • Estradiol measurement is not recommended.
  • Refer for pelvic ultrasonography (unless the diagnosis of PCOS is obvious on clinical and biochemical grounds):
    • To look for the classic picture of polycystic ovaries (12 or more follicles in at least one ovary, measuring 2–9 mm in diameter) or increased ovarian volume (greater than 10 mL) in women who satisfy only one of the above two criteria.
  • Exclude pregnancy and other diagnoses as appropriate — see Differential diagnosis.

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