Intramuscular ACTH stimulation test for assessment of adrenal function.
OBJECTIVES
Adrenal insufficiency is often diagnosed by short synacthen test using intravenous Injection Synacthene, which is not marketed in India officially. To overcome this problem this study was planned to validate and use Acton Prolongatum (Ferring pharmaceuticals) as intramuscular ACTH stimulation test for evaluation of adrenal function.


METHODS
This study was planned in two groups. First group called validation group, was studied for validation of intramuscular ACTH test and second group called study group, was evaluated for efficacy of intramuscular ACTH test to detect adrenal insufficiency. Twenty five units of ACTH (Acton Prolongatum) was injected intramuscularly and blood sample was collected after 60 minutes for estimation of cortisol. All subjects with one hour post ACTH cortisol < 18.0 microg/dl were diagnosed as having adrenal insufficiency.


RESULTS
This study was carried out in 61 subjects in validation group and 89 patients in study group. Basal and post ACTH serum cortisol were within normal range in healthy adults, patients with diabetes mellitus and primary hypothyroidism in validation group. Basal cortisol ranged from 4.67-18.39 microg/dl and post ACTH serum cortisol ranged from 20.01-44.95 microg/dl in these groups. Patients with known adrenal insufficiency had significantly low basal cortisol level than controls (2.86 +/- 2.66 vs. 10.35 +/- 4.37 microg/dl, p < 0.001), and post ACTH serum cortisol was < 18.0 microg/dl in all. Among study group 37 patients (41.6%) were diagnosed as adrenal insufficiency using post ACTH cortisol levels. Basal cortisol (< 3.0 microg/dl) could detect only 60% of these patients. Basal cortisol level has sensitivity of 60% and specificity of 100% to detect AI when compared to ACTH stimulated cortisol levels.


CONCLUSION
Intramuscular ACTH test using Acton Prolongatum is effective in evaluation of adrenal function in all suspected cases of primary or secondary adrenal insufficiency. Basal cortisol has poor sensitivity to diagnose AI.