In etanercept-treated psoriatic arthritis patients clinical improvement correlated with an increase of serum cortisol relative to other adrenal hormones.

OBJECTIVE In patients with rheumatoid arthritis (RA), long-term therapy with anti-tumor necrosis factor (TNF) antibodies sensitizes the pituitary gland and improves adrenal androgen secretion in prednisolone-naïve patients. However, whether this is similar in psoriatic arthritis (PsA) is not known. The aim of this study was to assess the effect of 12 weeks of etanercept treatment upon the function of the HPA axis in patients with PsA. METHODS Eleven prednisolone-naïve patients (mean age 47.3+/-8.9 years) with PsA were included. We measured serum levels of adrenocorticotropic hormone (ACTH), 17-hydroxyprogesterone (17OHP), cortisol, and androstenedione (ASD), at baseline and at 4 and 12 weeks after initiation of anti-TNF therapy (etanercept, 50 mg every week as a single dose by sc. injection). Clinical improvement was assessed using the Disease Activity Score-28 (DAS-28). RESULTS Mean levels of serum ACTH, serum cortisol, serum 17OHP and serum ASD did not markedly change during 12 weeks of etanercept treatment. Similarly, the ratio of serum cortisol divided by serum ACTH did not change during 12 weeks of anti-TNF treatment. However, an increase of serum cortisol relative to serum 17OHP or ASD was related to clinical improvement. This indicates that improvement was linked to higher serum cortisol levels relative to others adrenal hormones. CONCLUSION This is the first study to demonstrate baseline serum levels and the course of HPA axis-related hormones in patients with PsA. An increase of serum cortisol relative to others adrenocortical hormones (i.e., androstenedione and ACTH) was accompanied by clinical improvement.