Objective: To study prospectively the serum prolactin (PRL) concentrations among male patients with systemic lupus erythematosus (SLE) and their possible relationship to disease activity and manifestations.
Methods: Serum PRL levels were measured by radioimmunoassay in 31 male patients with SLE and 31 age matched controls. Demographic, clinical, and laboratory features of the patients were obtained. Mean PRL levels from both groups were compared, and PRL from patients with SLE was correlated with variables of disease activity, including the SLE Disease Activity Index (SLEDAI), complement level, and anti-dsDNA titer. Thirteen patients were followed serially and changes in PRL levels in relation to fluctuation in disease activity were evaluated.
Results: Mean PRL levels were higher in male patients with SLE than healthy controls; however, the difference did not reach statistical significance (230 vs 194 mIU/l; p = 0.06). Hyperprolactinemia was found in 4 patients (13%) and was not associated with particular clinical manifestations or autoantibodies. Considering all patients as a whole, PRL levels did not correlate with variables of disease activity and there was no difference in PRL between patients with active versus inactive disease. A subanalysis of the 4 hyperprolactinemic patients revealed a higher SLEDAI score than those with normal PRL (8.8 vs 3.7; p = 0.20); however, the difference was not statistically significant. Among the hyperprolactinemic patients, PRL levels did not correlate with SLEDAI score or anti-dsDNA titer. Prospective studies of PRL levels in 13 patients did not indicate a role of PRL in the monitoring of disease activity or predicting relapses.
Conclusion: Hyperprolactinemia occurred in a small proportion of male patients with SLE and its significance remained unclear. Serum PRL level did not correlate with disease activity and was not a reliable marker for disease monitoring.