Prolactin levels in patients with systemic lupus erythematosus: a case controlled study

Recent accumulated evidence suggests that prolactin (PRL) is an important immunomodulator and might have a role in the pathogenesis of systemic lupus erythematosus (SLE). Our aim was to assess the frequency of hyperprolactinemia in women with SLE and to evaluate its correlation with disease activity. PRL plasma levels were measured in 36 women with SLE and 20 age-matched healthy controls. We excluded patients with renal and/or hepatic failure, pregnant patients and patients taking drugs which could increase PRL levels. Disease activity was assessed using the SLE disease activity index (SLEDAI). Patients with a score > 10 were considered active. In patients and controls, PRL levels were determined by radioimmunoassay (RIA) during the first part of the menstrual cycle (between the 5th and 8th day) (normal value < 20 ng/ml). Ten of 36 (27.7%) SLE patients had high PRL levels (> 20 ng/ml). The mean PRL level was higher in SLE than in the control group (17.1+/-12.9 s.d. vs 9.9+/-3.5, P < 0.01). Patients with active disease had a trend to higher mean PRL levels than inactive patients although this difference was not statistically significant (21.1+/-4.8 vs 14.8+/-6.9, P = 0.09). No correlation was found between PRL levels and SLEDAI score. Furthermore, no significant correlation was found between PRL levels and any clinical or serological finding.