In certain patients with autoimmune diseases (AID) and with rheumatoid arthritis (RA), moderate hyperprolactinemia can be present.
Aim: Our aim was to investigate free PRL levels in RA, using two different PRL assays known to react with a different sensitivity to MPRL. The relationship between PRL and the disease-specific autoantibodies (antibody to cyclic citrullinated peptide:cCP-Ab and antinuclear antibody:AN-Ab) were analyzed also.
Methods: Eighty six patients were studied (68 women, 18 men, 56±16 years of age). 34 patients suffered from RA, 27 from other AID. 25 non autoimmune patients with osteoarthritis (NAI) were used for controls. AN-Ab (ELISA,Hycor), cCP-Ab (ECLMA,Roche) and PRL levels before and after PEG treatment (FPRL) were measured. PRL was assayed with two methods (Roche and Abbott). The latter PRL method reacts stronger with MRPL.
Results: Four hyperprolactinemic patients were found (2 RA, 2 AID). Higher total PRL levels were found in AI (RA and AID) patients (284±116 IU/l) than in NAI patients (197±78 IU/l) with the ECLMA method but not by CLMA method. FPRL levels were significantly lower in the NAI as compared to AID or RA (216±106 and 227±117 U/l) patients. FPRL and cCP-Ab correlated negatively (r=-0.39; P<0.01) in RA, while FPRL and cCP-Ab correlated positively (r=+0.84, P<0.001) in AID.
Conclusion: PRL levels are higher in AI than in NAI, but there was no difference between RA and AID cases. The correlations between FPRL and autoantibodies may explain the suspected role of PRL in the pathogenesis of RA and AID, however further investigations are needed to estimate the value of these findings.