A 27-year-old woman comes to the office for evaluation of infertility. She and her husband… — USMLE Step 2 CK

A 27-year-old woman comes to the office for evaluation of infertility. She and her husband have been trying to conceive for 14 months without success. Her last menstrual period was 7 months ago; prior to that, her menses occurred irregularly every 40 to 60 days. The patient reports a 4-kg (8.8-lb) weight gain over the past year, generalized fatigue, and occasional morning headaches. She notes mild worsening of facial acne. She takes no medications and has no other medical conditions. Her BMI is $24 \text{ kg/m}^2$ . Blood pressure is $110/70 \text{ mmHg}$ and pulse is $62/\text{min}$ . Physical examination shows a few open comedones on her chin but no hirsutism, clitoromegaly, or galactorrhea. Pelvic examination is unremarkable.

Laboratory results are as follows:

Human chorionic gonadotropin: negative
Follicle-stimulating hormone: $2.2 \text{ mIU/mL}$
Luteinizing hormone: $1.8 \text{ mIU/mL}$
Prolactin: $18 \text{ ng/mL}$
Thyroid-stimulating hormone (TSH): $1.0 \text{ mIU/L}$ (normal: 0.5–5.0)
Free thyroxine (T4): $0.5 \text{ ng/dL}$ (normal: 0.9–1.7)
Total testosterone: $35 \text{ ng/dL}$ (normal: 15–70)

Which of the following is the most appropriate next step in management?

Magnetic resonance imaging of the brainCevap
B
Initiation of levothyroxine therapy
C
Measurement of serum 17-hydroxyprogesterone
D
Administration of clomiphene citrate
E
Pelvic ultrasonography

Cevap

Magnetic resonance imaging of the brain

This patient presents with infertility, secondary amenorrhea, weight gain, fatigue, and headaches. Her laboratory results demonstrate a low free T4 alongside an inappropriately normal TSH, which is the classic diagnostic pattern for central (secondary) hypothyroidism. Furthermore, her FSH and LH levels are low despite 7 months of amenorrhea, indicating concurrent hypogonadotropic hypogonadism. The presence of multiple anterior pituitary hormone deficiencies in combination with morning headaches is highly suspicious for a space-occupying structural lesion in the sellar or suprasellar region, such as a nonfunctioning pituitary macroadenoma or craniopharyngioma. The most appropriate next step in management is magnetic resonance imaging of the brain to evaluate the pituitary gland. It is critical to image the brain and evaluate for concomitant central adrenal insufficiency (via serum cortisol and ACTH testing) before initiating any thyroid hormone replacement. Administering levothyroxine to a patient with undiagnosed central adrenal insufficiency increases cortisol clearance and can precipitate an acute, life-threatening adrenal crisis.

Adım Adım Çözüm

Interpret the thyroid function tests.

Low free T4 (

0.5 \text{ ng/dL}

) with an inappropriately normal TSH (

1.0 \text{ mIU/L}

This specific pattern identifies central (secondary) hypothyroidism rather than primary hypothyroidism.

Analyze the reproductive hormone panel.

Low FSH and LH in the setting of prolonged secondary amenorrhea.

This indicates concurrent hypogonadotropic hypogonadism, ruling out primary ovarian insufficiency.

Synthesize the clinical and laboratory findings.

Multiple anterior pituitary hormone deficiencies accompanied by new-onset morning headaches.

The combination strongly points to a structural lesion in the sellar or suprasellar region (e.g., nonfunctioning pituitary macroadenoma).

Determine the next best step in management.

Magnetic resonance imaging of the brain.

Imaging is required to visualize the pituitary gland and hypothalamus to formally diagnose the structural cause before any hormone replacement therapy is initiated.

Anahtar Kavram

Evaluation of infertility and secondary amenorrhea caused by hypopituitarism (central hypothyroidism and hypogonadotropic hypogonadism).

Soru

Cevap

Adım Adım Çözüm

Anahtar Kavram

Sık Yapılan Hatalar

Konular

Bu konudan daha fazla soru