Low dose (1 μg) adrenocorticotropin stimulation test in the evaluation of hypothalamopituitary-adrenal axis in patients with active pulmonary tuberculosis

Adrenocortical function in patients with active pulmonary tuberculosis is a debate of matter. Previous studies related to adrenocortical function in patients with active pulmonary tuberculosis demonstrated a high rate of suboptimal cortisol response to standard dose ACTH (250 μg) stimulation test. The aim of this study was to assess the hypothalamopituitary-adrenal (HPA) axis in low dose (1 μg) and standard dose ACTH (250 μg) stimulation tests in the patients with active pulmonary tuberculosis. Twenty-seven patients and 21 healthy subjects were included in the study. Cortisol levels were measured before, 30 and 60 min after ACTH (1 μg or 250 μg iv) injection. Cortisol responses to 1 μg ACTH at 30 and 60 min were significantly higher in the patient group than in the control group (p<0.05). Peak cortisol levels were significantly higher in the patient group than in the control group after both 1 μg and 250 μg ACTH administration (p<0.05). Cortisol responses to 250 μg ACTH at 30 and (at 30 and 60) 60 min were significantly higher in the patient group than in the control group (p<0.05). Peak cortisol levels obtained after 250 μg ACTH and after 1 μg ACTH were similar in the patient group (p>0.05). This study shows that 1 μg ACTH iv gives an equivalent peak cortisol value to 250 μg ACTH in patients with activated HPA axis. The cortisol levels obtained at 08:00, 11:00, 17:00 and 24:00 h were significantly higher in the patients than in the controls. This study clearly shows that HPA axis is activated in active pulmonary tuberculosis rather than underactivated.