Reproducibility of the low-dose corticotropin (ACTH) stimulation test in ICU patients with sepsis and/or septic shock

The low-dose ACTH stimulation test represents an accepted method to assess the adequacy of cortisol secretion. However, it remains currently unclear whether this test is reproducible in the setting of critical illness.

In this prospective study, we wished to investigate the reproducibility of the low-dose ACTH stimulation test in a group of severely ill patients.

To this end, 51 patients (40 men) with sepsis and/or septic shock, having a median age of 59 years (range: 17–82 years) were included. Two consecutive stimulation tests were carried out within 48 hours as follows: 1 μg freshly prepared tetracosactrin (1–24) was administered as an intravenous bolus and 30 min later a second blood specimen was obtained to measure stimulated cortisol levels.

The first test revealed that baseline and stimulation cortisol levels were 19 ± 7 μg/dl and 25 ± 8 μg/dl, respectively. The second test showed that baseline and stimulated concentrations were 19 ± 7 μg/dl and 24 ± 9 μg/dl, respectively. There was a good positive correlation between cortisol responses obtained following the two stimulation tests (Spearman's correlation coefficient, r = 0.65, P < 0.005).

We conclude that in critically ill patients with sepsis and/or septic shock, cortisol responses after stimulation with the low-dose test are fairly reproducible. This suggests that a single stimulation may be sufficient to assess adrenal function in such patients.