What laboratory evaluations are recommended for a patient suspected of having Polycystic Ovary Syndrome (PCOS)?

Laboratory Evaluations for Suspected Polycystic Ovary Syndrome (PCOS)

The comprehensive laboratory workup for suspected PCOS should include thyroid-stimulating hormone, prolactin, total testosterone or free testosterone, a two-hour oral glucose tolerance test, and fasting lipid profile to properly diagnose PCOS and assess metabolic complications. 1

Core Diagnostic Tests

• Androgen Assessment:

  • Total testosterone or bioavailable/free testosterone levels (preferably using mass spectrometry for highest accuracy) 1
  • Consider androstenedione if testosterone levels are normal but clinical suspicion remains high 1
  • DHEAS (Dehydroepiandrosterone sulfate) to rule out non-classical congenital adrenal hyperplasia 1

• Thyroid Function:

  • Thyroid-stimulating hormone (TSH) to exclude thyroid disease as a cause of menstrual irregularity 2, 1

• Prolactin Level:

  • Morning resting serum prolactin to exclude hyperprolactinemia 1

• Glucose Metabolism:

  • Two-hour oral glucose tolerance test with 75g glucose load to screen for glucose intolerance and type 2 diabetes 2, 1

• Lipid Profile:

  • Fasting lipid panel including total cholesterol, LDL cholesterol, HDL cholesterol, and triglyceride measurements 2, 1

Additional Tests to Consider

• Gonadotropin Levels:

  • LH and FSH measured between days 3-6 of menstrual cycle (LH/FSH ratio >2 suggests PCOS) 1, 3

• Progesterone:

  • Mid-luteal phase progesterone to confirm anovulation (levels <6 nmol/L indicate anovulation) 1

• Anti-Müllerian Hormone (AMH):

  • Elevated AMH levels correlate with PCOS diagnosis, with a threshold value of ≥35 pmol/l (5 ng/ml) showing high sensitivity (92%) and specificity (97%) 2, 4

Metabolic Screening

• Insulin Resistance Markers:
  • Fasting glucose/insulin ratio (ratio >4 suggests normal insulin sensitivity) 1
  • Calculate body mass index (BMI) to assess obesity 2, 1
  • Measure waist-hip ratio to identify central obesity (WHR >0.9 indicating truncal obesity) 2, 1

Exclusion of Other Conditions

• Screen for Cushing's Syndrome if patient has buffalo hump, moon facies, hypertension, abdominal striae, central fat distribution, easy bruising, or proximal myopathies 2, 1

• Consider Androgen-Secreting Tumors if there is rapid onset of symptoms, severe hirsutism, or very high testosterone levels 2, 1

• Rule Out Congenital Adrenal Hyperplasia with elevated DHEAS levels 1

• Assess for Acromegaly if coarse facial features or enlarged hands/feet are present 1

• Check for Primary Ovarian Failure using FSH levels 1

Important Considerations

• The Rotterdam criteria for PCOS diagnosis requires the presence of at least two of the following three criteria: chronic anovulation, hyperandrogenism (clinical or biochemical), and polycystic ovaries 5, 6

• Laboratory evaluations should be interpreted in context with clinical findings, including hirsutism, acne, balding, menstrual irregularities, and obesity 2, 7

• Ultrasound criteria for polycystic ovarian morphology have evolved - using endovaginal ultrasound with 8MHz frequency, the threshold is ≥20 follicles per ovary and/or ovarian volume ≥10ml 2

• Free testosterone levels are more sensitive than total testosterone for establishing androgen excess 5

• All women with PCOS should be screened for metabolic abnormalities due to the increased risk of type 2 diabetes, dyslipidemia, and cardiovascular disease 2, 7