Greater trochanteric pain syndrome (GTPS) is a common clinical entity for which the most effective treatment is local corticosteroid injection (LCI). There are no studies on the effect of LCI among patients with GTPS on the hypothalamic-pituitary-adrenal axis. The present study recruited nonselected patients diagnosed with GTPS. After consenting, participants received low dose (1 mu g) of adrenocorticotropin hormone (ACTH) stimulation test at 09:00. Immediately following the test, participants received a LCI of 80 mg of methylprednisolone acetate at the greater trochanteric region. The ACTH stimulation test was repeated 1, 2, 4, and 6 weeks following the LCI. Cortisol samples were obtained at just prior to (basal) and 30 min (post-stimulation) following every ACTH stimulation test. Serum cortisol levels of < 500 mu mol/l obtained 30 min following the ACTH stimulation test were considered evidence of secondary adrenal insufficiency. The study enrolled 22 patients, 21 of whom completed participation. There were 19 female participants (similar to 90%), and mean age of all the participants was 55.2 +/- 8.6 years. Four participants showed evidence of secondary adrenal insufficiency, which was observed only at weeks 1 and 2 following the LCI. Mean serum cortisol level among these four participants 30 min following the ACTH stimulation test was 354 mu mol/l, with a range of 268-430 mu mol/l. LCI of 80 mg of methylprednisolone acetate in the greater trochanteric area among patients with GTPS was associated with transient secondary adrenal insufficiency in similar to 20% of the patients, mainly 1 week following the injection.