INCIDENCE AND CHARACTERISTICS OF MICROPROLACTINOMAS (3-5 MM) IN 4199 WOMEN ASSAYED FOR PROLACTIN

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. The age of the patients ranged from 14-43 yrs with a greater prevalence of the younger ages (38% consulted and 56.5% manifested their symptoms before the age of 26 yrs). Provocative tests performed in 37 patients and in 37 subjects with non-tumorous hyperPRL-aemia (NT-HyperPRL) gave ambiguous results when basal PRL ranged from 30 to 49 ng/ml but the response was negative in all cases with micro-PRL-oma and in the majority of cases with NT-HyperPRL when basal PRL was 50-100 ng/ml. Independently of PRL levels, the patients with micro-PRL-omas presented with all the spectrum of menstrual disorders. Secondary amenorrhoea was the most common symptom (46%). Thirteen patients (12.5%) presenting with menses of normal length had PRL varying from 30 to 100 and in one case up to 230 ng/ml. Galactorrhoea was found in 63.5 % of the patients with micro-PRL-omas. However, 1/3 of the patients with high PRL levels (> 50 ng or > 100 ng) did not have spontaneous or provoked galactorrhoea at the time of the examination.