What is the optimal timing for hormone tests in relation to the menstrual cycle for patients with Polycystic Ovary Syndrome (PCOS) and an Intrauterine Device (IUD)?

Hormone Testing Timing in PCOS Patients with IUD

For patients with PCOS and an IUD, hormone tests should be performed during the early follicular phase (days 3-6 of the menstrual cycle), regardless of IUD presence, as the IUD does not interfere with hormone measurement timing. 1

Optimal Testing Window

• LH and FSH should be measured between cycle days 3-6, ideally calculated from an average of three blood samples taken 20 minutes apart during this window 1
• Testosterone should be measured on days 3-6 of the cycle to assess hyperandrogenism, which is the most sensitive biochemical marker for PCOS (abnormal in 70% of cases) 2
• Progesterone should be measured during the mid-luteal phase (approximately 7 days before expected menses) to assess ovulation status, with levels <6 nmol/L indicating anovulation 1

Key Hormone Tests for PCOS Diagnosis

The most diagnostically useful hormones in order of sensitivity are:

• Total testosterone (most frequently abnormal at 70% sensitivity) - measure on days 3-6 2
• Androstenedione (53% sensitivity) - measure on days 3-6 2
• LH/FSH ratio (only 35-44% sensitivity, should NOT be used as sole diagnostic criterion) 2
• DHEAS to rule out adrenal pathology (age-dependent cutoffs apply) 1

Critical Considerations for IUD Users

• The presence of an IUD does not alter hormone testing timing - standard early follicular phase timing (days 3-6) remains appropriate 1
• For patients with irregular cycles or amenorrhea (common in PCOS), testing can be performed on any random day, though interpretation may be more challenging 1, 3
• Levonorgestrel-releasing IUDs may cause amenorrhea, but this does not preclude hormone testing - proceed with testing when clinically indicated without waiting for menses 1, 4

Ultrasound Timing

• Pelvic ultrasound should be performed on days 3-9 of the cycle to assess for polycystic ovarian morphology (>10 peripheral cysts of 2-8 mm diameter) 1
• The ovarian stroma/total area ratio has 100% sensitivity and specificity for PCOS diagnosis and correlates strongly with androgen levels 3

Common Pitfalls to Avoid

• Do not rely solely on LH/FSH ratio - it has poor sensitivity (35-44%) and should be abandoned as a standalone diagnostic criterion 2
• Do not measure hormones post-ictally in patients with epilepsy, as prolactin may be falsely elevated 1
• Do not assume ovulation based on regular cycles alone - measure mid-luteal progesterone to confirm ovulatory status, as polycystic ovarian morphology can exist with regular ovulatory cycles 5
• Ensure laboratory-specific reference ranges are used, as absolute gonadotropin values vary significantly between assay methods 2

Additional Metabolic Assessment

• Fasting glucose and insulin should be measured in the morning to assess insulin resistance, which is present in many PCOS patients regardless of hyperinsulinemia 1, 6
• Glucose/insulin ratio >4 suggests reduced insulin sensitivity 1
• Insulin resistance is present even in women with polycystic ovarian morphology and regular cycles, making this assessment important regardless of menstrual pattern 5