What laboratory tests and evaluations are necessary to diagnose Polycystic Ovary Syndrome (PCOS)?

From the Guidelines

Diagnosing Polycystic Ovary Syndrome (PCOS) requires a comprehensive laboratory evaluation alongside clinical assessment, with the essential tests including hormonal assays such as total and free testosterone, dehydroepiandrosterone sulfate (DHEAS), androstenedione, luteinizing hormone (LH), follicle-stimulating hormone (FSH), and sex hormone-binding globulin (SHBG) as recommended by the most recent guidelines 1. The diagnosis of PCOS is based on the presence of two of three criteria: clinical or biochemical hyperandrogenism, oligo/anovulation, and polycystic ovaries on ultrasound, after excluding other endocrine disorders.

• Hormonal assays:
  • Total and free testosterone
  • Dehydroepiandrosterone sulfate (DHEAS)
  • Androstenedione
  • Luteinizing hormone (LH)
  • Follicle-stimulating hormone (FSH)
  • Sex hormone-binding globulin (SHBG)
• Metabolic evaluations:
  • Fasting glucose
  • Hemoglobin A1C
  • 2-hour oral glucose tolerance test to assess insulin resistance
• Cardiovascular risk evaluation:
  • Complete lipid panel
• Rule out other conditions:
  • Thyroid function tests (TSH, free T4)
  • Prolactin levels
  • 17-hydroxyprogesterone to exclude congenital adrenal hyperplasia
• Transvaginal ultrasound to visualize ovarian morphology, looking for the presence of 25 or more follicles measuring 2-9mm in diameter or increased ovarian volume (>10mL) as per the revised criteria by the Androgen Excess and Polycystic Ovary Syndrome Society 1. These tests should be performed during the early follicular phase (days 3-5) of the menstrual cycle when possible for accurate hormone assessment.
• It is crucial to note that the diagnosis of PCOS requires a combination of clinical, laboratory, and imaging evaluations, and no single test can confirm the diagnosis.
• The use of liquid chromatography-tandem mass spectrometry (LC-MS/MS) is considered the reference standard for assessing steroids, including androgens, but its use is limited by technical complexity and accessibility 1.
• The measurement of other androgens or androgen precursors such as androstenedione (A4), dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEAS), and dihydrotestosterone (DHT) are also available, but the lack of consensus in reference ranges based on population characteristics such as ethnicity and age poses challenges for clinicians in choosing the most reliable and accurate approach for assessing PCOS-related biochemical hyperandrogenism 1.

From the Research

Laboratory Tests for Diagnosing PCOS

To diagnose Polycystic Ovary Syndrome (PCOS), several laboratory tests and evaluations are necessary. These tests help confirm the presence of PCOS and rule out other conditions that may have similar symptoms. The following are some of the key laboratory tests used in the diagnosis of PCOS:

• Hormone level tests:
  • Luteinizing hormone (LH) levels: Elevated LH levels are common in women with PCOS 2, 3, 4
  • Follicle-stimulating hormone (FSH) levels: FSH levels are often lower than LH levels in women with PCOS 2, 3, 4
  • Testosterone levels: Elevated testosterone levels are a common feature of PCOS 2, 3, 4
  • Prolactin levels: Elevated prolactin levels can be present in some women with PCOS 3, 5
• Metabolic tests:
  • Fasting blood glucose: To evaluate insulin resistance and glucose metabolism 2, 5
  • Lipid profile: To evaluate the risk of cardiovascular disease 3, 5
  • HbA1c: To evaluate long-term glucose control 2, 5
• Imaging tests:
  • Pelvic ultrasound: To evaluate the presence of polycystic ovaries 2, 6

Evaluation of PCOS Diagnosis

The diagnosis of PCOS is primarily clinical, based on the presence of at least two of the three Rotterdam criteria: oligoanovulation, hyperandrogenism, and polycystic ovaries on ultrasonography 6. Laboratory tests play a crucial role in confirming the diagnosis and ruling out other conditions. A thorough medical history, clinical evaluation, and standardized blood samples are essential for diagnosing PCOS 6, 5.

Additional Tests

Other tests that may be ordered to evaluate PCOS include:

• Thyroid function tests: To rule out hypothyroidism 3
• Adrenal function tests: To rule out congenital adrenal hyperplasia 4
• Insulin sensitivity tests: To evaluate insulin resistance 5
• Lipid profile tests: To evaluate the risk of cardiovascular disease 3, 5