Low-dose, not low-risk: potential adrenal suppression identified by a risk-based approach to ACTH testing

Area of Science:

• Rheumatology
• Endocrinology
• Pharmacology

Background:

• Low-dose glucocorticoid (GC) maintenance therapy is common in rheumatic diseases.
• Adrenal suppression is a known side effect of GC therapy.
• The frequency and factors associated with impaired adrenal response during low-dose maintenance GC therapy require further investigation.

Purpose of the Study:

• To determine the prevalence of impaired adrenal response on the Synacthen test in patients with rheumatic diseases on low-dose maintenance GC therapy.
• To identify factors associated with impaired adrenal response in this patient population.

Main Methods:

• A retrospective observational study of 48 patients with autoimmune rheumatic diseases on maintenance GC therapy (prednisolone ≤ 5 mg/day).
• Adrenal function was assessed using the Synacthen test, with impaired response defined by low baseline cortisol and inadequate response to stimulation.
• Statistical analyses included Mann-Whitney U, Fisher's exact, and ROC analyses to evaluate dose, duration, cumulative dose, and history of methylprednisolone pulse therapy.

Main Results:

• Impaired adrenal response was observed in 62.5% of the studied patients (30 out of 48).
• Patients with impaired response had significantly higher cumulative GC doses, lower baseline cortisol, and more frequent histories of methylprednisolone pulse therapy.
• An optimal cumulative GC dose cutoff of 10,371.5 mg (prednisolone equivalent) was identified for impaired adrenal response.

Conclusions:

• Impaired adrenal response is frequent in rheumatic disease patients receiving low-dose maintenance GC therapy.
• Higher cumulative GC exposure and prior pulse therapy are associated with impaired adrenal response.
• A risk-based approach to adrenal evaluation is recommended, even during low-dose GC treatment, as adrenal suppression can occur in stable patients.