The Incidence of Adrenal Insufficiency in Myeloma Patients Receiving Pulse-Dose Dexamethasone

Introduction: Glucocorticoids (GC's) are major drugs in the treatment of multiple myeloma (MM). Chronic administration of supra-physiological doses of GC's suppresses the hypothalamus-pituitary-adrenal (HPA) axis and is associated with secondary adrenal insufficiency (AI). In MM, GC's are usually administered in weekly high dose pulses. Due to long GC-free periods in such therapy, GC-induced AI is not usually considered to be a consequence of GC therapy in MM (Krasner, AS. JAMA, 1999. 282(7): p. 671-6). Here we report on the incidence of AI in MM patients treated at our center with pulse-dose GC.

Methods: This is a retrospective cross-sectional study of patients with MM treated with GC-based regimens. Patients were required to have at least a random serum cortisol or a standard 250 mcg ACTH stimulation test result available in their medical record during dexamethasone-based chemotherapy. Patients were excluded if they were on dexamethasone more than 1 day a week, were lost to follow-up, had prior use of synthetic progestational agents such as megestrol or had been on oral glucocorticoids for any other medical indication. Diagnosis of AI was established by a frankly low AM serum cortisol level (<3 ug/dL) or an inadequate cortisol response to ACTH stimulation test (Salvatori, R. JAMA, 2005. 294(19): p. 2481-8).

Results: A total of 45 patients were included in this study with median age of 62 (range, 49-89). Fifteen (33.3%) of patients were diagnosed with AI. The median random cortisol level in AI group was 2.3 ug/dL (range, 0.3-7.4 ug/dL) compared to 9.9 ug/dL (range, 1.0-21.2 ug/dL) in the non-AI group. The median time between the last dexamethasone dose and the serum cortisol assay was 5 days (range, 1-21). The median number of GC-based chemotherapy cycles taken before diagnosis of AI was 15 (range, 2-60). The median cumulative dexamethasone consumption was 1280 mg (range, 180-5220 mg). There was no correlation between developing AI and dose or duration of dexamethasone treatment. We observed clinical trend between cumulative doses of ≥1500 mg (P= 0.055) or use of clarithromycin (P=0.079) and developing AI, without reaching a statistically significant difference.

Conclusion: The rate of AI was 33% among patients with MM on weekly pulse-dose dexamethasone. As such, patients should be periodically evaluated for this to enable early detection and proper management.