Evaluation and Management of Amenorrhea with Elevated LH and Normal FSH
The next step in this case should be a progesterone challenge test to assess endometrial response and help differentiate between polycystic ovary syndrome (PCOS) and functional hypothalamic amenorrhea (FHA). 1
Clinical Assessment of Current Findings
Your laboratory results show:
- Negative serum hCG (ruling out pregnancy)
- Elevated LH (12.3)
- Normal FSH (5.71)
- LH:FSH ratio of approximately 2.15:1
- Normal prolactin levels
- Normal thyroid function
These findings are most consistent with PCOS, particularly given the elevated LH:FSH ratio >2, which is characteristic of PCOS 1. However, further evaluation is needed to confirm this diagnosis.
Diagnostic Algorithm
Progesterone Challenge Test
- Administer oral progesterone (such as 200mg daily for 10 days) 2
- Monitor for withdrawal bleeding within 7 days after completing progesterone
- A positive test (withdrawal bleeding) indicates adequate estrogen levels and patent outflow tract
- A negative test suggests hypoestrogenism or outflow tract abnormality
Pelvic Ultrasound
- To evaluate for polycystic ovarian morphology
- Assess endometrial thickness (indicator of estrogen status)
- Rule out structural abnormalities
Additional Laboratory Testing
- Consider testosterone levels to assess for hyperandrogenism
- Fasting glucose/insulin ratio to evaluate for insulin resistance
- Consider estradiol levels if available
Interpretation of Progesterone Challenge Results
If Positive Challenge (Withdrawal Bleeding):
- Confirms adequate estrogen levels and patent outflow tract
- With elevated LH:FSH ratio >2, strongly suggests PCOS 1
- Further evaluation should focus on metabolic parameters (glucose tolerance, lipid profile)
If Negative Challenge (No Withdrawal Bleeding):
- May indicate hypoestrogenism despite the laboratory values
- Consider evaluation for FHA with PCOM (functional hypothalamic amenorrhea with polycystic ovarian morphology) 1
- Assess for energy deficit, excessive exercise, stress, or weight loss
Clinical Pearls and Pitfalls
Important Distinction: The LH:FSH ratio exceeding 2 strongly suggests PCOS, as recent data shows that approximately 82% of FHA patients have an LH:FSH ratio <1 1
Caution with Interpretation: Up to 60% of women with FHA may still have withdrawal bleeding after progesterone challenge, making this test helpful but not definitive 1
Avoid Missing Pituitary Pathology: With elevated LH and normal FSH, it's important to ensure normal prolactin levels, as you have done. If prolactin had been elevated, pituitary MRI would be warranted to rule out adenoma 1, 3
Consider Lifestyle Factors: Even with laboratory values suggesting PCOS, assess for energy deficit, stress, or excessive exercise which could indicate a mixed picture of FHA-PCOM 1
Management Plan Based on Diagnosis
If PCOS is confirmed:
- Cyclic progesterone therapy (e.g., 200mg daily for 10-12 days monthly) to prevent endometrial hyperplasia 2
- Lifestyle modifications focusing on weight management if BMI elevated
- Consider metabolic evaluation (lipids, glucose tolerance)
- Oral contraceptives if contraception is desired
If FHA is diagnosed:
- Address underlying causes (energy deficit, stress, excessive exercise)
- Ensure adequate calcium intake and consider bone density testing if prolonged amenorrhea 1
- Estrogen replacement therapy if prolonged hypoestrogenism to protect bone health
Remember that accurate diagnosis is crucial as the management approaches differ significantly between PCOS and FHA, with PCOS requiring cyclic progesterone to prevent endometrial hyperplasia, while FHA primarily requires addressing the underlying cause of hypothalamic dysfunction.