About informative value of very high prolactin levels in patients presenting with prolactin-secreting pituitary macroadenomas (clinical observations)

Abstract

The mean blood prolactin level in patients with microprolactinomas is usually 3000-4000 mU/l compared with 10 000-20 000 mU/l in cases presenting with macroprolactinomas. It may be as high as 1 mln mU/l and more in patients with a giant tumour. The measurement of prolactin levels requires laboratory studies of strongly diluted plasma samples. Significant dilution is fraught with erroneous prolactin levels: nevertheless, this approach allows a tendency toward decreasing concentration of prolactin to be revealed which may be important for taking rapid decision concerning the choice of the treatment strategy (either surgical or medicamental) especially in critical situations. A few clinical cases of giant prolactinomas with an unusually high blood prolactin level are described with reference to its dynamics during treatment with cabergoline.