A 24-year-old nulliparous woman is evaluated in the clinic for secondary amenorrhea. Her l… — USMLE Step 2 CK

A 24-year-old nulliparous woman is evaluated in the clinic for secondary amenorrhea. Her last menstrual period occurred $8$ months ago. Previously, she had predictable $28$ -day cycles. Over the past $6$ months, she has become increasingly distressed by new-onset severe cystic acne, coarse hair growth on her chest and back, and a noticeable deepening of her voice. She has no significant past medical history and takes no medications. In the clinic, a urine human chorionic gonadotropin test is negative. Vital signs are normal with a body mass index of $22$ $kg/m^2$ . Examination reveals temporal hair thinning, marked hirsutism, and clitoromegaly. Pelvic examination is otherwise unremarkable. Laboratory studies show:

Laboratory Test	Result	Reference Range
Thyroid-stimulating hormone	$1.8$ $\mu U/mL$	$0.5-5.0$ $\mu U/mL$
Prolactin	$12$ $ng/mL$	$<25$ $ng/mL$
Total testosterone	$68$ $ng/dL$	$15-70$ $ng/dL$
Dehydroepiandrosterone sulfate (DHEA-S)	$890$ $\mu g/dL$	$35-430$ $\mu g/dL$

Which of the following is the most appropriate next step in the diagnostic evaluation of this patient?

A
Pelvic ultrasonography
B
Initiation of combined oral contraceptives
Computed tomography of the abdomenAnswer
D
Endometrial biopsy
E
Measurement of late-night salivary cortisol

Answer

Computed tomography of the abdomen

The correct answer is computed tomography of the abdomen. This patient presents with secondary amenorrhea and rapid-onset virilization (clitoromegaly, temporal thinning, voice changes), which is highly suspicious for an androgen-secreting tumor. The laboratory evaluation is crucial for localizing the tumor. Dehydroepiandrosterone sulfate (DHEA-S) is specifically synthesized by the adrenal glands, whereas testosterone is secreted by the ovaries (and peripherally converted). Her isolated, marked elevation in DHEA-S (>700 µg/dL) strongly suggests an adrenal source, such as an adrenocortical carcinoma or adrenal adenoma. Therefore, abdominal imaging (CT or MRI) is the most appropriate next step.

Step-by-Step Solution

Rule out pregnancy as a cause of secondary amenorrhea.

The urine beta-hCG is negative, allowing for further endocrine and structural evaluation.

Pregnancy is the most common cause of secondary amenorrhea and must be excluded first in all premenopausal women.

Analyze the physical examination findings to categorize the severity of hyperandrogenism.

The patient exhibits signs of true virilization, including clitoromegaly, deepening voice, and temporal balding, rather than just mild hirsutism or acne.

Rapid onset of virilizing signs in a female suggests an autonomous, malignant, or rapidly growing androgen-secreting tumor rather than a benign disorder like polycystic ovary syndrome.

Interpret the laboratory results to localize the source of the excess androgens.

Total testosterone is within normal limits, while DHEA-S is markedly elevated (>700 µg/dL).

Dehydroepiandrosterone sulfate (DHEA-S) is produced almost exclusively by the adrenal glands. Conversely, significant elevations in total testosterone (>150 ng/dL) typically originate from the ovaries.

Select the appropriate imaging modality based on the localized source.

Computed tomography (CT) of the abdomen is selected to visualize the adrenal glands.

Because the laboratory profile specifically points to an adrenal source of androgen excess (high DHEA-S), abdominal imaging is required to identify a suspected adrenal adenoma or adrenocortical carcinoma.

Key Concept

In premenopausal women presenting with rapid-onset virilization and secondary amenorrhea, markedly elevated DHEA-S levels indicate an adrenal androgen-secreting tumor, warranting an abdominal CT scan. Elevated testosterone levels point to an ovarian source, warranting a pelvic ultrasound.

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