Prolactinoma/Pituitary Gland Tumor

Hey there! I was just diagnosed with prolactinoma-- I have been doing some research and noticed that most people have had MRIs done to confirm a tumor before treatment-- my doctor only tested my prolactin levels and saw they were a bit above average and prescribed medication for one month and then said we will re-test my levels. Is this standard practice? What are your experiences with prolactinoma?