Initial Workup for Amenorrhea in a 38-Year-Old Female
The initial workup for a 38-year-old female with amenorrhea should include serum FSH, LH, prolactin, and TSH levels after confirming the negative pregnancy test, followed by a progesterone challenge test to assess estrogen status and outflow tract patency. 1
Step 1: Confirm Pregnancy Status
- The negative urine pregnancy test is a good start, but serum hCG should be considered for definitive exclusion of pregnancy, as it is the most common cause of amenorrhea 1
Step 2: Initial Laboratory Testing
- Obtain the following laboratory tests:
- Follicle-stimulating hormone (FSH)
- Luteinizing hormone (LH)
- Prolactin
- Thyroid-stimulating hormone (TSH)
Step 3: Progesterone Challenge Test
- Administer medroxyprogesterone acetate 10 mg daily for 5-10 days
- Withdrawal bleeding within 2-7 days after completing the progesterone indicates:
- Adequate estrogen levels
- Patent outflow tract
- Likely anovulation (common in PCOS)
- No bleeding indicates either:
- Hypoestrogenic state
- Outflow tract obstruction
Step 4: Further Evaluation Based on Initial Results
If Elevated Prolactin:
- Obtain pituitary imaging (MRI preferred) to rule out pituitary adenoma 2
- Check medications that may cause hyperprolactinemia
- Evaluate for hypothyroidism (already checked with TSH)
If Elevated FSH (>40 IU/L):
- Indicates primary ovarian insufficiency
- Consider karyotype analysis, especially if patient is <40 years old
If Low/Normal FSH and LH with Negative Progesterone Challenge:
- Suggests hypothalamic amenorrhea
- Evaluate for:
- Recent weight changes
- Excessive exercise
- Psychological stress
- Eating disorders
If Normal/High LH:FSH Ratio (>2:1):
- Suggests polycystic ovary syndrome (PCOS)
- Check for clinical signs of hyperandrogenism (hirsutism, acne)
- Consider measuring testosterone and androstenedione levels
Important Considerations
- At 38 years old, this patient could be experiencing premature ovarian insufficiency or early perimenopause despite lack of vasomotor symptoms 2
- The absence of genitourinary symptoms of menopause does not rule out declining ovarian function
- Amenorrhea is defined as absence of menses for ≥6 months in a woman with previously regular cycles or ≥3 months in a woman with previously irregular cycles 2
Common Pitfalls to Avoid
- Don't assume perimenopause without appropriate testing, especially in a woman without vasomotor symptoms
- Don't forget to evaluate thyroid function, as thyroid disorders can cause amenorrhea
- Don't miss hyperprolactinemia, which is a common treatable cause of amenorrhea
- Don't neglect to consider structural causes if the progesterone challenge is negative despite normal estrogen levels
This systematic approach will help identify the underlying cause of amenorrhea in this 38-year-old patient and guide appropriate treatment to prevent long-term complications such as osteoporosis, endometrial hyperplasia, and cardiovascular disease.