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Difficulty: HardReproductive Endocrinology and Infertility

A 27-year-old woman comes to the clinic seeking evaluation for primary infertility. She and her male partner have been having regular, unprotected intercourse for 14 months without conception. The patient notes that her menstrual cycles have always been unpredictable, occurring roughly every 45 to 90 days. She also reports bothersome dark hair growth on her chin, upper lip, and chest, which she removes weekly. She has no history of sexually transmitted infections or pelvic pain. Her body mass index is 29 kg/m², and her blood pressure is 118/76 mmHg. Physical examination reveals terminal hairs in a male-pattern distribution and mild facial acne, but there is no deepening of the voice, temporal balding, or clitoromegaly. Striae and proximal muscle weakness are absent. Pelvic ultrasound shows bilaterally enlarged ovaries, each containing over 15 small peripheral cysts. Morning laboratory tests obtained on day 3 of a progestin-induced withdrawal bleed show the following:

Laboratory TestResultReference Range
Thyroid-stimulating hormone1.8 µU/mL0.5-5.0 µU/mL
Prolactin14 ng/mL< 20 ng/mL
Total testosterone60 ng/dL15-70 ng/dL
Dehydroepiandrosterone sulfate2.1 µg/mL0.6-3.3 µg/mL
17-hydroxyprogesterone1,150 ng/dL< 200 ng/dL

Which of the following is the most likely diagnosis?

  1. A
    Polycystic ovary syndrome
  2. B
    Secondary hypothyroidism
  3. Non-classic congenital adrenal hyperplasiaAnswer
  4. D
    Androgen-secreting ovarian tumor
  5. E
    Cushing syndrome

Answer

The most likely diagnosis is non-classic congenital adrenal hyperplasia.
The correct diagnosis is non-classic congenital adrenal hyperplasia (NCCAH). This patient presents with a classic triad of oligo-ovulation, clinical hyperandrogenism (hirsutism, acne), and polycystic ovaries on ultrasound. While these findings fulfill the Rotterdam criteria for polycystic ovary syndrome (PCOS), PCOS remains a diagnosis of exclusion. Current guidelines mandate ruling out other potential causes of hyperandrogenism. This patient's markedly elevated early morning 17-hydroxyprogesterone level (1,150 ng/dL) is the critical distinguishing factor. In NCCAH, a partial deficiency of the 21-hydroxylase enzyme prevents the normal conversion of 17-hydroxyprogesterone to 11-deoxycortisol. The accumulated 17-hydroxyprogesterone is shunted into the androgen synthesis pathway, leading to excess testosterone and the resulting clinical signs. A basal morning level greater than 800-1,000 ng/dL is considered diagnostic for 21-hydroxylase deficiency, making this the correct diagnosis rather than PCOS.

Step-by-Step Solution

1
Evaluate the patient's clinical presentation and ultrasound findings.
The patient has oligomenorrhea, hirsutism, and polycystic ovaries on ultrasound.
This triad fulfills the Rotterdam criteria, but requires the exclusion of other hyperandrogenic disorders to make a final diagnosis.
2
Analyze the laboratory results to rule out mimicking endocrinopathies.
TSH and prolactin are normal, ruling out thyroid disease and hyperprolactinemia. 17-hydroxyprogesterone is markedly elevated at 1,150 ng/dL.
A basal morning 17-hydroxyprogesterone level above 200 ng/dL is suspicious, and a level above 800-1,000 ng/dL is diagnostic for 21-hydroxylase deficiency.
3
Synthesize findings to arrive at the final diagnosis.
The high 17-hydroxyprogesterone level confirms that the patient's hyperandrogenism is of adrenal origin rather than idiopathic ovarian origin.
The 21-hydroxylase enzyme deficiency causes precursor accumulation and shunting toward androgen synthesis, perfectly explaining her PCOS-like presentation.

Key Concept

Evaluation of hyperandrogenism and infertility requires measuring 17-hydroxyprogesterone to distinguish polycystic ovary syndrome (a diagnosis of exclusion) from non-classic congenital adrenal hyperplasia.
Estimated Time:1m 30s
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Topics

Reproductive Endocrinology and Infertility

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