Comparison of 1 μg ACTH, 250 μg ACTH and glucagon tests for assessment of the hypothalamo-pituitaryadrenal axis in healthy subjects
Fatih Tanriverdi1, Ayhan Lale2, Zuleyha Karaca1, Mustafa Kula3, Kursad Unluhizarci1 & Fahrettin Kelestimur1
Objectives: Evaluation of the HPA axis is still a big challenge. This study was performed to compare 1 μg ACTH, 250 μg ACTH and glucagon tests for evaluation of HPA axis in healthy male and female subjects with different ages.
Materials and methods: This study was carried out on 57 healthy individuals (29 men, 28 women) between 20 and 70 years of age (the number and gender of the subjects are approximately equal for each decade). Low dose short synacthen test (1 μg ACTH), conventional dose short synacthen test (250 μg ACTH) and glucagon tests were performed consecutively, and there was at least 48 h time between each test.
Results: Mean peak cortisol value in 250 μg ACTH test was significantly higher than 1 μg ACTH and glucagon tests. Mean peak cortisol value in 1 μg ACTH was similar to glucagon test. Sex and age did not effect mean peak cortisol values in each test. There were significant correlations between the peak cortisol value in 250 μg ACTH and 1 μg ACTH tests, 250 μg ACTH and glucagon tests. But there was not a correlation between 1 μg ACTH and glucagon tests. While cut-off level of peak cortisol accepted as 18 μg/dl the sensitivities of 1 μg ACTH, 250 μg ACTH and glucagon tests were calculated as 86, 98.2 and 54.4%, respectively.
Conclusion: Conventional dose short synacthen test has the highest sensitivity in the evaluation of HPA axis in healthy subjects. These findings clearly suggest that to obtain more accurate results in 1 μg ACTH and glucagon tests appropriate cut off values are required. In all the three tests, age and gender do not seem to have an impact on the results of the HPA axis evaluation.