Table 1:

Initial investigations and differential diagnoses for polycystic ovarian syndrome

Test	Results		Alternative diagnoses	Next steps
Test	Expected results for patient with PCOS	Results for a patient with an alternative diagnosis	Alternative diagnoses	Next steps
Prolactin	Normal	Markedly elevated	Pituitary tumour	Repeat early morning, fasting prolactin Test macroprolactin Consider pituitary MRI Referral to endocrinology
TSH	Normal	Elevated	Hypothyroidism	Repeat TSH Test free T4 Consider levothyroxine supplementation Consider referral to endocrinology
TSH	Normal	Depressed	Hyperthyroidism	Repeat TSH Measure T3/T4, refer to endocrinology
FSH, LH and estradiol	Normal–high LH and normal FSH in the context of low follicular phase estradiol	High FSH and LH in the context of low follicular phase estradiol	POI	Repeat test in 4 wk Refer to gynecology or endocrinology
FSH, LH and estradiol		Low FSH, LH and estradiol	Hypogonadotropic hypogonadism	Repeat test in 4 wk Refer to gynecology or endocrinology
β-hCG	Negative	Positive	Pregnancy
17-OHP	Normal	Elevated	Non-classic adrenal hyperplasia	Refer to endocrinology
Calculated free testosterone, total testosterone and free androgen index	Normal–mildly elevated	Markedly elevated total testosterone (> 5.2 nmol/L) (14)	Ovarian or adrenal tumour	Transvaginal ultrasonography Adrenal CT or MRI Refer to endocrinology or gynecologic oncology
Androstenedione	Normal–mildly elevated	Markedly elevated	Non-classic adrenal hyperplasia or possible adrenal tumour	Refer to endocrinology
Dehydroepiandrosterone sulfate	Normal–mildly elevated	Elevated (> 18.9 μmol/L) (14)	Adrenal tumour	Adrenal CT or MRI Refer to endocrinology
Transvaginal ultrasonography	PCOM (≥ 10 mL ovarian volume or ≥ 20 follicles in either ovary)	Ovarian tumour		Refer to gynecology
Anti-müllerian hormone	Typically greater than 34 pmol/L (15)	Undetectable	POI (if age < 40 yr)	Refer to gynecology or endocrinology
Anti-müllerian hormone	Typically greater than 34 pmol/L (15)	Low	Age-related decline in ovarian reserve	Refer to gynecology or endocrinology

Note: CT = computed tomography, FSH = follicle-stimulating hormone, LH = luteinizing hormone, MRI = magnetic resonance imaging, PCOM = polycystic ovarian morphology, PCOS = polycystic ovarian syndrome, POI = premature ovarian insufficiency, TSH = thyroid-stimulating hormone, 17-OHP = 17-hydroxyprogesterone, β-hcg = β-human chorionic gonadotropin.