Question

A 23-year-old female college student presents with amenorrhea for 10 months. She had menarche at age 14 and normal regular menses every 28 days until this year. She is in good health and not taking any medications. She is 5 feet 4 inches tall and weighs 130 pounds. Her examination, including a pelvic exam, is normal. Beta-hCG is < 5 mIU/mL, and TSH is 5.0 mU/L (normal 0.35-6.7 mU/L). What is the most appropriate next diagnostic test to help determine the cause of amenorrhea in this patient?

A. Serum 17-hydroxyprogesterone level
B. Serum prolactin level
C. Pelvic ultrasound
D. Serum LH and FSH levels
E. Brain MRI

Answer 1

The most appropriate next diagnostic test for a 23-year-old female with amenorrhea for 10 months, normal exams, and normal TSH is to measure serum prolactin levels, as hyperprolactinemia is a common cause that can lead to amenorrhea.

Step-by-step explanation:

In the case presented, where a 23-year-old female college student is exhibiting amenorrhea for 10 months with otherwise normal examinations and hormone levels, the most appropriate next diagnostic test to help determine the cause of amenorrhea would be B. Serum prolactin level. This is because a common cause of amenorrhea is hyperprolactinemia, which can suppress the hypothalamic secretion of GnRH, leading to a decrease in the secretion of FSH and LH from the pituitary gland, resulting in anovulation and amenorrhea. Prolactin levels would be crucial in diagnosing such a condition. Moreover, considering her Thyroid Stimulating Hormone (TSH) levels are within the normal range, primary hypothyroidism is less likely to be the cause, and her negative Beta-hCG excludes pregnancy.

Options such as serum 17-hydroxyprogesterone would be considered if there were suspicion of congenital adrenal hyperplasia, and a pelvic ultrasound could help identify anatomical causes. Measurement of serum LH and FSH levels could be helpful; however, given that the patient has had normal menstruation until recently, an assessment of prolactin levels would be prioritized. Lastly, Brain MRI is not indicated unless there is a suggestion of the presence of a pituitary tumor, which typically would be accompanied by other signs or symptoms not present in this case.