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Difficulty: EasyMenstrual Cycle Abnormalities and Contraception

An otherwise healthy 29-year-old woman is evaluated in the outpatient clinic for a 7-month history of absent menses. Menarche occurred at age 12, and her menstrual cycles were previously regular, occurring every 28 to 30 days. She runs 15 miles per week and consumes a balanced diet. Her body mass index is 22 kg/m². She takes no daily medications and has no history of chronic medical conditions. A urine human chorionic gonadotropin test is negative. Physical examination reveals normal breast development without galactorrhea. There is no evidence of hirsutism, acne, or clitoromegaly. Pelvic examination is unremarkable. Which of the following is the most appropriate next step in the evaluation of this patient?

  1. Measurement of serum prolactin, thyroid-stimulating hormone, and follicle-stimulating hormoneAnswer
  2. B
    Measurement of serum testosterone and dehydroepiandrosterone sulfate
  3. C
    Magnetic resonance imaging of the pituitary gland
  4. D
    Endometrial biopsy
  5. E
    Reassurance and observation for an additional 6 months

Answer

The correct next step is the measurement of serum prolactin, thyroid-stimulating hormone (TSH), and follicle-stimulating hormone (FSH).
The correct answer accurately reflects the standard algorithmic approach to secondary amenorrhea. Secondary amenorrhea is defined as the cessation of menses for at least 6 months in women with previously regular cycles. Once pregnancy is ruled out with a negative human chorionic gonadotropin test, the initial laboratory evaluation must assess the hypothalamic-pituitary-ovarian axis and rule out common systemic causes. Measuring serum prolactin, thyroid-stimulating hormone (TSH), and follicle-stimulating hormone (FSH) achieves this by screening for hyperprolactinemia, thyroid disease (such as primary hypothyroidism), and primary ovarian insufficiency.

Step-by-Step Solution

1
Identify the patient's primary diagnosis based on the clinical presentation.
The patient has secondary amenorrhea, defined as the absence of menses for 6 months or more in a woman with previously regular cycles.
Establishing the correct diagnostic category determines the appropriate clinical pathway.
2
Determine the first required test for any premenopausal woman presenting with amenorrhea.
A urine human chorionic gonadotropin (hCG) test must be performed. In this case, it is negative, excluding pregnancy.
Pregnancy is the most common cause of secondary amenorrhea and must be ruled out before proceeding with further evaluation.
3
Apply the standard diagnostic algorithm for secondary amenorrhea after a negative pregnancy test.
The next step is to obtain serum levels of prolactin, TSH, and FSH.
These tests evaluate for the most common endocrine etiologies of secondary amenorrhea: hyperprolactinemia, thyroid dysfunction, and primary ovarian insufficiency.

Key Concept

Initial Laboratory Evaluation of Secondary Amenorrhea
Estimated Time:1m 0s
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Topics

Menstrual Cycle Abnormalities and Contraception

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