Difficulties and controversies still exist in the diagnosis of small (3-5 mm) prolactinomas (micro-PRL-omas). In the present study serum prolactin (PRL) was assayed in 4199 women aged 14-43 years belonging to 4 groups: A: 753 women with normal cycles (NC) and infertility (control group), B: 2523 with menstrual disorders, C: 519 with NC and hirsutism, D: 404 with galactorrhoea. The distribution of PRL values from 1 to 30 ng/ml was almost similar in the subjects of group A, B and C. Within this range the vast majority of subjects (91%, 92.2% and 88% respectively in these 3 groups and 83% in group D) had PRL levels from 1 to 15 ng/ml and together with the proportion of subjects with PRL values 16 to 20 ng/ml they included 96.7% of the entire mixed population. A proportion of scattered outlying PRL values above 30 ng/ml was found in each group (A = 2%, B = 3%, C = 1% and D = 28.7%) and in this subset 117 prolactinomas (PRL-omas) were found, 19 (23%) in the 83 subjects with PRL levels 31-49 ng/ml and 98 (75.3%) in the 130 subjects with PRL values greater than or equal to 50 ng/ml. Of the 117 PRL-omas 9 were bigger than 10 mm and 4 had a size from 6 to 9 mm. In the remaining 104 the size was presumed from direct or indirect radiological evidence to be 3-5 mm.(ABSTRACT TRUNCATED AT 250 WORDS)

It is concluded that bromocriptine LAR is an effective treatment in the majority of patients with macroprolactinomas; it is also partially effective in some patients with GH secreting macroadenomas.