Recommended blood tests

• These recommendations are based on guidelines from the Royal College of Obstetricians and Gynaecologists [RCOG, 2007].
• Total testosterone level is normal to moderately elevated in women with PCOS.
• High testosterone levels (greater than 5.0 nanomol/L) warrant investigation to exclude conditions such as late-onset congenital adrenal hyperplasia, Cushing's syndrome, or an androgen-secreting tumour [RCOG, 2007].
• A proportion of women with PCOS do not have an abnormality in their circulating androgens [Rotterdam ESHRE/ASRM-Sponsored PCOS Consensus Workshop Group, 2004]. A study of 1741 women with PCOS found that only 29% had elevated serum testosterone (greater than 2.5 nanomol/L) [Balen et al, 1995].
• Combined oral contraceptives may normalize testosterone levels [Legro, 2007].
• Sex hormone-binding globulin (SHBG) provides a surrogate measure of the degree of hyperinsulinaemia.
• Insulin suppresses SHBG [Jayagopal et al, 2003; Balen et al, 2005].
• If the SHBG level is low despite an apparently normal total testosterone level, the amount of free testosterone (which is the bioactive form) may be increased, therefore elevating the free androgen index (FAI) [Balen et al, 2005].
• A small cross-sectional study of 12 women with PCOS found that serum SHBG levels were a useful marker for insulin resistance [Jayagopal et al, 2003].
• The FAI (or free testosterone) measurement is the most sensitive method of assessing hyperandrogenaemia [Rotterdam ESHRE/ASRM-Sponsored PCOS Consensus Workshop Group, 2004]. If the SHBG and total testosterone levels are known, the FAI can be calculated. The FAI provides a simple assessment of the amount of physiologically-active testosterone present. Free testosterone may reflect the combined effects of:
• Insulin resistance (increased insulin level and decreased SHBG level).
• Ovarian and adrenal hyperandrogenism (increased total circulating testosterone) [Legro, 1998].
• Thyroid-stimulating hormone and prolactin.
• Prolactin levels may be normal or mildly elevated in PCOS [Balen et al, 2005]. About 10–25% of women with PCOS have mildly elevated prolactin levels [Practice Committee of the American Society for Reproductive Medicine, 2008].
• Although thyroid-stimulating hormone is a useful screening test, the incidence of thyroid dysfunction among women with hyperandrogenism is no higher than that in women without hyperandrogenism who are of reproductive age [Balen et al, 2005].

Tests not recommended for the diagnosis of PCOS but essential for the diagnosis of other conditions that may present with amenorrhoea

• Luteinizing hormone (LH)/follicle-stimulating hormone (FSH) ratios are no longer considered useful in diagnosing PCOS because of their inconsistency [RCOG, 2007].
• The FSH level is normal in PCOS [Azziz et al, 2009].
• The LH level may be moderately elevated in PCOS [Azziz et al, 2009]. A single blood sample may fail to detect an increased LH level because of the pulsatile nature of gonadotrophin release [Dunaif, 1997; McIver et al, 1997]. A study of 1741 women with polycystic ovaries and other features of PCOS found that 39% had increased LH (greater than 10 IU/L) [Balen et al, 1995].
• Measurement of FSH and LH are essential in the diagnosis of other conditions that may present with amenorrhoea [Balen et al, 2005].
• Estradiol measurement is not recommended, as levels tend to fluctuate, and can be normal or low in both PCOS and hypothalamic amenorrhoea [Practice Committee of the American Society for Reproductive Medicine, 2008]. Estrogenization may be confirmed by endometrial assessment [Balen et al, 2005].

Pelvic ultrasonography

• The recommendation to do pelvic ultrasonography to assess ovarian morphology is based on expert advice in a textbook [Balen et al, 2005].
• Polycystic ovaries do not have to be present to make the diagnosis, and the finding of polycystic ovaries does not alone establish the diagnosis. In some women, the combination of irregular menses and biochemical hyperandrogenism may obviate the need for pelvic ultrasonography if there is confidence in the diagnosis.