Objective: Prolactin (PRL) and growth hormone (GH) are pituitary hormones with immunomodulating properties. Their upregulated secretion may play a role in the pathogenesis of chronic inflammatory diseases. We evaluated PRL and GH responses to secretion stimulus in patients with rheumatoid arthritis (RA) and ankylosing spondylitis (AS).
Methods: Insulin hypoglycemia (0.1 IU/kg) was induced in 15 women with RA, 18 men with AS, and healthy controls matched for age, sex and body mass index. Plasma concentrations of glucose, PRL, GH, interleukin 6 (IL-6), and tumor necrosis factor alpha (TNF-a) were analyzed.
Results: RA patients had significantly lower area under the curve (AUC) of PRL (p = 0.049) compared to RA controls. During hypoglycemia double or higher increase of plasma PRL occurred in 5 RA (33%) patients and in 8 RA controls (57%). Using the General Linear Model procedure, no significant differences in PRL or GH responses were observed in patients with RA and AS. TNF-a was higher in patients with RA compared to RA controls (p < 0.05). There was no significant difference in TNF-a concentrations between AS patients and AS controls. IL-6 was higher in RA patients compared to controls (p < 0.05) and in AS patients compared to controls (p < 0.01). Significant positive correlation was found between TNF-a levels and AUC of PRL in AS patients (r = 0.46, p = 0.047), but not in the 2 control groups or in RA patients.
Conclusion: Our results indicate no upregulated PRL or GH responses to stimulation in premenopausal women with RA or men with AS.