Use of the Dexamethasone-Corticotrophin Releasing Hormone Test to Assess Hypothalamic-Pituitary-Adrenal Axis Function in Rheumatoid Arthritis

Abstract EN

Objectives.

Hypothalamic-Pituitary-Adrenal axis function may be abnormal in rheumatoid arthritis (RA).

A pilot study in 7 patients suggested impaired glucocorticoid feedback in some patients after the dexamethasone-corticotrophin releasing hormone (CRH) test.

This study aimed to investigate the dexamethasone-corticotrophin releasing factor test in a larger group of patients and relate the results to characteristics of the disease.

Methods.

Outpatients with active RA (≥3 swollen and tender joints and C-reactive protein > 10 mg/L) took dexamethasone (1.5 mg) at 23:00 hour in the evening.

Next day, baseline saliva and plasma samples were collected, CRH was infused at 11:00 hour, and 4 serial blood and saliva samples were collected.

Plasma samples were stored at −80∘C and a radioimmunoassay performed for saliva and plasma cortisol.

Results.

All 20 participants showed normal dexamethasone suppression and mounted no response to the CRH challenge.

In samples with measurable cortisol, there was a strong correlation between saliva and plasma values (r = 0.876, n = 26, P<.01).

Conclusion.

No abnormalities were found in the Dexamethasone-CRH test in RA patients in contrast to a previous pilot study.

Salivary cortisol measurement may offer an alternative noninvasive technique to plasma cortisol in RA patients in future studies.