Evaluating tertiary adrenal insufficiency in rheumatology patients on long-term systemic glucocorticoid treatment.

Sagar, Rebecca; Mackie, Sarah; Morgan, Ann W; Stewart, Paul; Abbas, Afroze

BACKGROUND Patients with rheumatic diseases are often treated with prolonged, high-dose systemic glucocorticoids which can cause hypothalamic-pituitary-adrenal (HPA) axis suppression and development of tertiary adrenal insufficiency. Adrenal insufficiency carries the risk of serious, potentially life-threatening adrenal crisis. Our study evaluated the prevalence, characteristics and recovery of patients with underlying rheumatology conditions who had received prolonged glucocorticoid treatment. METHODS We retrospectively evaluated 238 patients, managed in accordance with current nationally and internationally accepted clinical guidelines. Data collected included patient demographics, historical steroid data, 09.00h cortisol/short synacthen test (SST) results and follow-up data on those with repeat assessments. RESULTS Overall, 65% of our cohort had a 09.00h cortisol <350nmol/l. On SST, 43% of patients demonstrated evidence of possible tertiary adrenal insufficiency. Prednisolone equivalent dose at time of SST was significantly higher in the group who failed SST versus those who passed; mean of 5.57mg versus 3.59mg (p= 0.005). 09.00h cortisol result correlated with 30-minute cortisol on SST (R2 = 0.20, p=0.002). 0-minute cortisol on SST correlated more strongly with 30-minute cortisol than 09.00h cortisol (R2 = 0.59, p-value <0.001). Patients with 0-minute cortisol >350nmol/L, all passed their SST. Patients who remained on prednisolone were more likely to recover (71%) versus those switched to hydrocortisone (27%), p= 0.02. Peak steroid dose was predictive of recovery; significantly lower in those who recovered (mean of 22.3mg versus 33.8mg, p= 0.03). Steroid duration was not found to be a predictor of recovery [recovery (64.2 months) versus non-recovery (55.6 months), p= 0.58]. There was no correlation found to outcome on SST with age, sex, peak steroid dose, steroid duration, underlying rheumatological condition, additional exogenous steroid use or serum sodium. CONCLUSION 43% of our patients demonstrated sub-optimal adrenal function on SST. Steroid dose at the time of SST was the only significant predictive risk factor for tertiary adrenal insufficiency. 09.00h cortisol demonstrated good correlation with outcome on SST and could represent a valid screening test to reduce need for SST if 09.00h >350nmol/L. Further prospective data is required to further characterise risk factors, predictive features of recovery and establish optimal management strategy of steroids (prednisolone vs hydrocortisone) to encourage adrenal recovery.