Adrenal function during tuberculous infection and effects of antituberculosis treatment on endogenous and exogenous steroids.

SETTING

To date, few studies have been published on the frequency of adrenal disorder during active tuberculosis and whether rifampicin treatment has an adverse effect on adrenal function.

OBJECTIVE

We evaluated endogenous and exogenous steroid metabolism in patients with active tuberculosis before and during treatment to observe whether the functions were affected by tuberculosis and rifampicin.

DESIGN

Basal hormone levels and Synacthen stimulation test were obtained in 22 patients with active tuberculosis before and 20-30 days after antituberculosis treatment including rifampicin. Exogenous steroid metabolism was assessed by 1 mg overnight dexamethasone suppression test before and during antituberculosis treatment.

RESULTS AND CONCLUSION

No significant differences were found on basal plasma cortisol or adrenocorticotropic hormone levels, but significant decrements were found on basal dehydroepiandrosterone sulfate (P < 0.05) and urinary free cortisol levels (P < 0.01) before and after commencing antituberculosis treatment. After Synacthen stimulation, only one patient had insufficient increment in plasma cortisol levels. This patient was diagnosed as a case of Addison's disease. Although nine patients (42%) showed sufficient suppression of cortisol secretion on the dexamethasone test before treatment, none had sufficient suppression with dexamethasone after antituberculosis treatment. We found less mean maximum adrenal cortisol responsiveness to Synacthen stimulation during the course of antituberculosis treatment (P < 0.01). Although impairment of adrenal function is a rare condition in active tuberculosis, rifampicin may have a significant effect on steroid metabolism.