Changes in Serum Prolactin Levels	

In patients with macroadenomas, the serum prolactin levels can be readily suppressed with bromocriptine therapy. Figure 4.21 shows serum prolactin levels throughout the day after an initial 2.5-mg oral dose of bromocriptine administered at 0900 to the patient whose visual field plots and CT scans are shown in Figs. 4.19 and 4.20, respectively, as well as those from a patient with a similar problem. After a single dose of bromocriptine, the prolactin levels fell by approximately ninety per cent. The mean and absolute range of prolactin levels in samples taken at the same time intervals before therapy (baseline) and during bromocriptine therapy, 7.5 mg/d, are also shown in Fig. 4.21. In the first patient, the prolactin levels were suppressed into the normal range (less than 18ng/ml (360mu/l)) and in the second patient, prolactin levels, although lowered, did not return to normal.