Overview
Polycystic Ovary Syndrome (PCOS) is the most common endocrine condition in Australian women of reproductive age, affecting an estimated 8–13% — and up to 21% of Indigenous Australian women according to NHMRC data. It is characterised by a combination of irregular ovulation, elevated androgens (male-type hormones), and polycystic ovaries on ultrasound.
In Australia, PCOS is diagnosed using the international evidence-based guideline endorsed by the RACGP, RANZCOG and the Australian Monash PCOS Academy. The diagnosis is made when **two of the following three Rotterdam criteria** are met, after other causes have been excluded:
1. **Menstrual irregularity** — oligo-ovulation or anovulation (cycles longer than 35 days, fewer than 8 cycles a year, or absent periods). 2. **Biochemical or clinical hyperandrogenism** — elevated total or free testosterone, or clinical signs such as hirsutism, acne, or androgenic alopecia. 3. **Polycystic ovarian morphology on ultrasound** — 20 or more follicles per ovary or ovarian volume >10 mL (updated 2023 threshold for high-resolution transvaginal ultrasound).
A GP typically orders a PCOS blood test panel that includes LH, FSH, total testosterone, SHBG, free androgen index (FAI), prolactin, TSH, 17-hydroxyprogesterone, fasting glucose, fasting insulin and HbA1c. A pelvic ultrasound is usually ordered in parallel. Importantly, the 2023 international guideline states that **ultrasound is no longer required for diagnosis in adults if the other two Rotterdam criteria are present** — blood tests plus clinical history are sufficient.
Common Symptoms
- •Irregular, infrequent or absent menstrual periods
- •Difficulty becoming pregnant (anovulatory infertility)
- •Excess facial or body hair (hirsutism)
- •Acne, oily skin, or scalp hair thinning
- •Weight gain around the abdomen, or difficulty losing weight
- •Acanthosis nigricans (dark velvety skin patches — sign of insulin resistance)
- •Mood changes, anxiety, depression
- •Sleep disturbances or sleep apnoea
Key Blood Markers
LH (Luteinizing Hormone)
Often elevated; LH:FSH ratio reversedLH drives ovarian androgen production. In PCOS, LH is often elevated relative to FSH, producing an LH:FSH ratio >2:1 or 3:1. Sample should be taken on day 2–5 of the cycle where possible.
FSH (Follicle Stimulating Hormone)
Normal or lowFSH is typically normal or low in PCOS. The reversed LH:FSH ratio (LH > FSH) is a classic but not mandatory finding.
Total Testosterone
Often elevated (upper normal or above range)Elevated androgens are a core diagnostic criterion. Australian labs typically use LCMS for accuracy. Total testosterone >2.5 nmol/L in women is suspicious for hyperandrogenism.
SHBG (Sex Hormone Binding Globulin)
Often lowSHBG is commonly suppressed in PCOS due to hyperinsulinaemia, which increases the free (bioavailable) testosterone fraction even when total testosterone is borderline.
HbA1c
Normal to elevated (pre-diabetes range)Insulin resistance is present in 50–70% of women with PCOS regardless of BMI. HbA1c screens for pre-diabetes, which is significantly more common in PCOS.
Fasting Insulin
Often elevatedUsed alongside fasting glucose to calculate HOMA-IR, a surrogate for insulin resistance. The 2023 international PCOS guideline recommends screening for insulin resistance in all women with PCOS.
Prolactin
Normal (exclusion test)Ordered to exclude hyperprolactinaemia, which can cause cycle irregularity and mimic PCOS.
TSH
Normal (exclusion test)Ordered to exclude thyroid dysfunction, which can cause menstrual irregularity and mimic PCOS.
Frequently Asked Questions
What blood tests are used to diagnose PCOS in Australia?
What are the Australian diagnostic criteria for PCOS?
Can PCOS be diagnosed from blood tests alone?
What hormone levels indicate PCOS?
How do I get tested for PCOS in Australia?
Can you have a normal blood test and still have PCOS?
When in my cycle should I get the PCOS blood test?
Is PCOS testing covered by Medicare?
Quick Facts
- Key Markers:8
- Common Symptoms:8