Correlation of serum prolactin levels and disease activity in systematic lupus erythematosus

To assess the frequency of hyperprolactinaemia and its possible clinical significance in patients with systemic lupus erythematosus (SLE). In this cross-sectional study, we determined serum prolactin (PRL) levels in 60 SLE female patients (age range 15-60 years). Disease activity was defined according to the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI). Serum PRL concentrations were determined by immunoradiometric assay. Elevated serum concentrations of PRL (> 20 ng/ml) were found in 5 of 60 (8.4%) patients. No direct correlation between PRL levels with disease activity of SLE was found (r = 0.062, P = 0.39). SLE was active in 23 patients (SLEDAI a parts per thousand yen 6) and inactive in 37 (SLEDAI < 6). In those with active disease, median PRL levels were lower (11.0 ng/ml) than normoprolactinaemic group (12.1 ng/ml). There was no significant difference in serum PRL levels between active and non-active patients (P = 0.07). There was a significant difference in the frequency of several clinical manifestations and serological parameters between SLE patients with normal and high prolactin (renal involvement, haematological manifestation and anti-ds DNA). This study has shown that hyperprolactinaemia is prevalent in random SLE patients. The elevated PRL levels seem not to be associated with disease activity. The mechanism and pathoaetiological and clinical significance of hyperprolactinaemia in a small subset of SLE patients remain unclear and a longer follow-up is necessary.