A 34-year-old woman with a history of regular cycles presents with secondary amenorrhea for 6 months. Her serum prolactin level is significantly elev…

A 34-year-old woman with a history of regular cycles presents with secondary amenorrhea for 6 months. Her serum prolactin level is significantly elevated at $120 \text{ ng/mL}$ (normal < $20 \text{ ng/mL}$). She is not taking any medications and her TSH is normal. Magnetic resonance imaging (MRI) of the brain reveals a microadenoma of the pituitary gland ($6 \text{ mm}$). What is the most appropriate initial treatment?