In Reply: We thank Drs. Rodríguez-Gutiérrez and Gonzálvez-Gonzálvez and Dr. Keller for their thoughtful comments.
In our paper, we did not elaborate on the low-dose cosyntropin stimulation test. The 1-μg test, in particular, has been shown to have similar or better sensitivity, with similar or lower specificity, compared with the 250-μg dose, depending on the study design. Unfortunately, the administration of the 1-μg dose presents more technical difficulty than the 250-μg dose, thus limiting its use. Cosyntropin (used in the United States) comes in a vial with 250 μg of powder. This must be reconstituted with 250 mL of normal saline, and only 1 mL is to be given. Adherence to the plastic tubing may occur, and more precise timing is needed as the cortisol levels may decrease. 1–3
Responding to Dr. Keller, we were unable to find any systematic reviews comparing inhaled corticosteroids that have a “higher therapeutic index” as a class vs older inhaled corticosteroids. There are several studies, however, comparing individual inhaled corticosteroid preparations with each other in terms of adrenal effects, and we feel that it is beyond the scope of this response to perform a systematic analysis. In addition, the determination of adrenal function used in studies comparing one inhaled corticosteroid with another were varied, including cosyntropin stimulation tests and surrogates such as the urinary cortisolcreatinine ratio, a morning plasma cortisol level less than 5 μg/L, and serum cortisol concentration curves, preventing more definitive conclusions even if the data were to be pooled. 4–6 A double-blind, randomized study comparing the adrenal effects of ciclesonide and fluticasone showed a smaller reduction in the peak serum cortisol level achieved with ciclesonide compared with fluticasone, in both low-dose and high-dose cosyntropin stimulation tests, with the results in the ciclesonide group being similar to placebo. 7 However, the mean peak serum cortisol levels after exposure to these inhaled corticosteroids were not presented in table format, and the results have to be inferred from the figures and the narrative description of the baseline mean peak cortisol levels 8 (ie, before exposure to these inhaled corticosteroids). Case reports have suggested that changing the inhaled corticostseroid formulation from fluticasone to ciclesonide allowed for improvement of adrenal function. 8 The purported mechanism of decreased adrenal effects of ciclesonide is its greater deposition in the lungs and, hence, less entry into the systemic circulation and fewer systemic adverse effects. 9