Adrenocortical function in hospitalised patients with active pulmonary tuberculosis receiving a rifampicin-based regimen -- a pilot study

Abstract

Objective: To assess whether adrenocortical function was compromised in patients with active tuberculosis (TB) during the first 5 days of therapy with either a rifampicin-based or ciprofloxacin-based regimen.

Design: Patients were randomised into two groups of 10 each. Adrenocortical function was compared in both groups by the measurement of biochemical indices, electrolytes, osmolality and pituitary-adrenocortical hormones. Adrenal reserve was assessed by intravenous 250 mug adrenocorticotropin hormone (ACTH) stimulation tests.

Setting: Department of Medicine, Johannesburg Hospital.

Subjects: Twenty hospitalised patients who were diagnosed with TB.

Outcome measures: Respiratory rate, pulse rate and blood pressure were recorded, and urinary sodium and osmolality were measured. Serum ACTH, cortisol, dehydroepiandrosterone- sulphate (DHEA-S) and aldosterone were assayed.

Results: None of the patients demonstrated biochemical evidence of overt adrenal insufficiency. There were no significant differences between the two groups before or during therapy for any biochemical indices, electrolytes, hormones or calculated osmolality. Mean basal cortisol concentrations were substantially elevated and DHEA-S levels were consistently subnormal, resulting in a high cortisol/ DHEA-S ratio. In the ciprofloxacin group, cortisol responses to ACTH stimulation on day 1 were not significantly lower than on day 5. In the rifampicin group, cortisol concentrations decreased at each time point on day 5 compared with day 1 (p = 0.001). However, a significantly higher mean incremental rise from the basal cortisol concentration was measured on day 5 at 60 minutes (p = 0.04). In the entire cohort of 20 patients, 40% demonstrated an incremental cortisol rise of < 250 nmol/l after ACTH stimulation on day 1.

Conclusions: Rifampicin did not additionally impair adrenocortical function during the initial period of therapy. The high cortisol/DHEA-S ratio might be of clinical relevance.