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PCOS (hormonal measurements in suspected PCOS)

Last reviewed dd mmm yyyy. Last edited dd mmm yyyy

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Initial hormonal investigation should aim at excluding disorders of hypothalmic-pituitary-ovarian axis that cause ovulation disturbance. Measurements should ideally occur in the first week of the menstrual cycle and include:

  • testosterone, sex binding globulin, FSH, LH, PRL, TFTs

A diagnosis of PCOS is supported by:

  • elevated free testosterone levels (in saliva or plasma)

  • low levels of sex hormone binding globulin
    • to calculate the free androgen index (FAI), total testosterone value x 100 is divided by the sex hormone binding globulin value (1)
    • FAI levels of 5 and above are indicative for polycystic ovary syndrome (2)
      • other disorders presenting with clinical and/or biochemical signs of hyperandrogenism such as congenital adrenal hyperplasia, androgen-secreting tumours or Cushing syndrome should be excluded. For this purpose further laboratory testing, e.g. 17-OH-progesterone, follicle-stimulating hormone, oestradiol, prolactin or cortisol may be necessary

  • elevated LH:FSH ratio - usually, to more than 3:1; serum LH is raised with that of FSH relatively lower than in a normal menstrual cycle; measure in the first week of the menstrual cycle
    • however, an elevated LH:FSH ratio is no longer considered to be a diagnostic criterion for PCOS due to its inconsistency (1)

  • there may also be elevated androstenedione levels and high circulating levels of oestrone

Note that serum testosterone levels in patients with PCOS seldom exceed 4.8 nmol/l. If testosterone levels are greater than 4.8 nmol/l then further endocrinological investigation to exclude other causes of androgen hypersecretion (e.g. Cushing's syndrome, adrenal gland or ovarian tumours) (3).

Reference:


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