Impaired adrenal cortex reserve in patients with rheumatic and musculoskeletal diseases who relapse upon tapering of low glucocorticoid dose.

Objectives: To examine adrenal cortex reserve in patients with rheumatic and musculoskeletal diseases (RMD) who relapse upon tapering of low glucocorticoid dose, despite concomitant treatment with disease-modifying anti-rheumatic drugs (DMARDs).

Methods: A morning standard dose of 250 mcg tetracosactide (Synacthen test) was given in 25 consecutive patients (13 rheumatoid arthritis, 2 psoriatic arthritis, 5 systemic lupus erythematosus, 2 dermatomyositis, 1 systemic sclerosis, 2 temporal arteritis) at the time of relapse upon small reductions (1-2 mg daily) of low prednisolone dose (<7.5 mg daily), while being on stable concomitant treatment with methotrexate, leflunomide, hydroxychloroquine, azathioprine, mycophenolate, tofacitinib, belimumab, anti-TNF, anti-IL-6 or anti-IL-1 regimens (n=14; 3; 9; 1; 2; 1; 1; 5; 2; 1, respectively). Sex-matched apparently healthy individuals (n=45) served as controls.

Results: Baseline cortisol levels and time-integrated cortisol response to tetracosactide were lower in patients than controls (12.01±4.47 vs. 15.63±4.16 mcg/dl, p=0.001, and 1050±286 vs. 1284±182, p<0.001, respectively). No significant associations were observed between the cortisol response to tetracosactide and age, duration of disease or glucocorticoid treatment. An abnormal Synacthen test, indicative of adrenal insufficiency, presumably secondary to chronic glucocorticoid administration, was noted in 5/25 patients. The remaining 20 patients (80%) had normal Synacthen test demonstrating, however, lower cortisol response than controls, independently of age (β-coefficient=-0.373, p=0.033).

Conclusions: Patients with RMD in remission under DMARDs who relapse upon concomitant low glucocorticoid dose tapering should be tested for iatrogenic adrenal insufficiency. Whether a marginally normal Synacthen test should discourage further attempts to withdraw glucocorticoid treatment in these patients warrants further investigation.