12th April 2024

Investigations

PCOS can be diagnosed on clinical grounds; however, several investigations are useful in the workup. Biochemical tests include testosterone, prolactin, thyroid function tests, sex hormone binding globulin (SHBG), LH and FSH. Increased total testosterone and reduced level of SHBG (a protein which transports androgens) would be in keeping with PCOS. A ratio of LH/FSH ratio of >2.5:1 indicates a proportionally high amount of LH released from the follicular cysts, resulting in increased androgens. In a small proportion of patients, prolactin will be mildly increased.

Pelvic ultrasound can assess the number of cysts and ovarian volume. Patients may have impaired glucose tolerance due to insulin resistance. This can be screened with the oral glucose tolerance test and is recommended for all women with PCOS who are considering pregnancy or have risk factors, including BMI >25kg/m², >40 years of age or non-Caucasian ethnicity.

NICE guidance utilises the 2003 Rotterdam Consensus, where a diagnosis of PCOS requires two of the following, provided the other causes have been excluded.

Differential diagnosis includes thyroid dysfunction, acromegaly, hyperprolactinaemia and congenital adrenal hyperplasia.