What are the next steps in evaluating a patient with hirsutism and normal prolactin level?

Next Steps in Evaluating Hirsutism with Normal Prolactin

For a patient with hirsutism and normal prolactin levels, the next steps should include measuring serum luteinizing hormone (LH), follicle stimulating hormone (FSH), testosterone, androstenedione, dehydroepiandrosterone sulfate (DHEAS), thyroid function tests, and fasting glucose/insulin ratio, in addition to the already ordered transvaginal and pelvic ultrasound and lipid panel. 1, 2

Comprehensive Hormonal Evaluation

Gonadotropins and Sex Hormones

• Measure LH and FSH between days 3-6 of the menstrual cycle
  • Calculate LH/FSH ratio (>2 suggests polycystic ovary syndrome) 1
  • Obtain three measurements 20 minutes apart for accuracy
• Measure testosterone levels (days 3-6 of cycle)
  • Values >2.5 nmol/L suggest PCOS or valproate effect 1
• Measure androstenedione levels
  • Values >10.0 nmol/L warrant investigation for adrenal/ovarian tumors 1
• Measure DHEAS
  • Age-specific elevated levels may indicate non-classical congenital adrenal hyperplasia 1

Metabolic Assessment

• Measure fasting glucose and insulin levels
  • Calculate glucose/insulin ratio (>4 suggests insulin resistance) 1
  • Insulin resistance is common in both PCOS and idiopathic hirsutism 3

Imaging Studies

Already Appropriately Ordered

• Transvaginal ultrasound (optimal between days 3-9 of cycle)
  • Look for polycystic ovaries: >10 peripheral cysts, 2-8 mm diameter, with thickened ovarian stroma 1
• Pelvic ultrasound to evaluate for other structural abnormalities

Consider Additional Imaging

• If hormonal tests reveal significant abnormalities, particularly elevated androgens, consider adrenal imaging to rule out adrenal tumors 1

Special Considerations

Menstrual Pattern Assessment

• Document menstrual irregularities using a menstrual chart for at least 6 months
  • <23 days: polymenorrhoea

  • 35 days: oligomenorrhoea

  • No bleeding >6 months: amenorrhoea 1

Additional Testing Based on Clinical Findings

• If LH levels are low or low/normal with low testosterone, consider measuring estradiol levels, particularly if breast symptoms are present 1
• If thyroid function tests reveal hypothyroidism, this could be contributing to hirsutism 2

Potential Pitfalls and Caveats

• Hirsutism may be idiopathic (15% of cases) even with normal hormone levels and regular menstrual cycles 3
• Don't overlook medication-induced hirsutism - review all medications the patient is taking 2
• While prolactin is normal in this case, hyperprolactinemia and PCOS can coexist in rare cases 4
• Consider ethnic and genetic factors when evaluating hirsutism severity, as normal hair patterns vary by ethnicity 1
• Insulin resistance can be present in non-obese women with idiopathic hirsutism, even without PCOS 3

Following this comprehensive evaluation, the results will guide further management, which may include lifestyle modifications, hormonal therapy, or referral to endocrinology depending on the underlying cause identified.