The prevalence of hyperprolactinemia in patients with primary Sjögren's syndrome.

Objective: To assess the prevalence of hyperprolactinemia in 55 patients with primary Sjögren's syndrome (SS), and its clinical significance.
Methods: Concentrations of serum prolactin (PRL) were determined in 55 consecutive patients with primary SS and 110 controls by a fluoroimmunometric assay in a prospective case-control design.
Results: The 55 patients with primary SS had higher serum PRL than 110 matching controls (271.5 vs 205.9 mIU/l; p < 0.02), and this difference was most evident in patients diagnosed before the age of 45 years (374.8 vs 245.5 mIU/l; p < 0.05), a patient population characterized by active immunological disease. Serum PRL did not correlate to disease duration, serum immunoglobulin, autoantibodies, or focus score in biopsies from minor salivary glands, but did correlate to score for internal organ disease (r = 0.33, p < 0.05). Two patients were diagnosed as having primary SS 12 years after hyperprolactinemia was first detected, and both patients had aggressive primary SS as indicated by extraglandular manifestations. One of the patients developed primary SS after being treated with bromocriptine, an inhibitor of PRL synthesis, for 12 years.
Conclusion: Patients with primary SS have moderately increased levels of serum PRL, especially evident in patients diagnosed at a young age with active immunological disease. Serum PRL is correlated to index for internal organ disease, and primary SS may be preceded by hyperprolactinemia for many years.