Study of adrenal function in patients with tuberculosis

Abstract

Background: Although subclinical adrenal insufficiency has been documented in tuberculosis but it has been neglected in mainstream management of TB due to inconclusive data on its prevalence in TB. The fact that adrenal insufficiency may result not only in poor general condition of the patient but also sudden death due to adrenal crisis, makes it all the more important to address this issue seriously. In this non-randomized interventional study comprising of 100 cases of TB, our aim was to assess the adreno-cortical functions in patients with pulmonary TB (50 cases) and extra-pulmonary TB (50 cases) in an attempt to determine if there is any compromise of adrenal function.

Methods: In this study, 100 cases of active TB were investigated for adrenal insufficiency by measuring morning fasting basal serum cortisol levels, followed by low dose ACTH stimulation test using 1μg synacthen (synthetic ACTH analog). The post-stimulation serum cortisol levels were estimated. Basal serum cortisol levels<220nmol/L or post-stimulation test serum cortisol level increment<200nmol/L or post-stimulation serum cortisol levels<500nmol/L were suggestive of adrenal insufficiency.

Results: Basal serum cortisol level was low in 16% cases and after low dose ACTH stimulation test, cortisol response was subnormal in 76% cases. Incidence of adrenal insufficiency in pulmonary TB (74%) and extra-pulmonary TB (78%) were comparable. The number of females having adrenal insufficiency in both the groups was higher than the males (67.3% males and 83.3% females) but the difference was statistically significant only in extra-pulmonary TB group (p=0.011). On analysing the data, the sensitivity of basal serum cortisol level estimation in diagnosing adrenal insufficiency was observed to be 21.05% and its specificity was 100%. Positive predictive value was 100% and negative predictive value was 28.57%. Diagnostic accuracy of basal serum cortisol level estimation was observed to be 40%.

Conclusion: The incidence of subclinical adrenal insufficiency in TB cases attending chest department at a tertiary care hospital was significantly high but comparable in both pulmonary and extra-pulmonary type of TB. Females in general and particularly those with extra-pulmonary TB were observed to be at increased risk of adrenal insufficiency. The low dose ACTH stimulation test was able to identify cases with adrenal insufficiency which had normal basal serum cortisol levels. Screening all TB cases for adrenal insufficiency by measuring both morning basal serum cortisol levels and low dose ACTH stimulation test can help identify cases at risk of fatal adrenal crisis and institute timely management, thus improving disease prognosis.

Keywords: ACTH stimulation test; Adrenal function; Cortisol; Extra pulmonary tuberculosis; Tuberculosis.