Glucocorticoid-induced diabetes and adrenal suppression

To the Editor: We found the article by Drs. Lansang and Kramer¹ on glucocorticoid-induced diabetes and adrenal suppression in the November 2011 issue to be a useful and clinically oriented review. However, we strongly believe there is an issue that should be addressed.

It is well accepted that the short cosyntropin (Cortrosyn) stimulation test is the best screening maneuver for assessing adrenocortical insufficiency. The authors state, however, that 250 μg is preferable to lower doses (10 μg or 1 μg), since these are not yet widely accepted, and refer to an article by Axelrod from 1976.²

Based on studies showing that 250 μg of cosyntropin is a pharmacologic rather than a physiologic stimulus that may overstimulate partially atrophied or mildly dysfunctional adrenal glands, multiple studies in the last 20 years have shown that the low-dose test has an equal or better result than the classic 250-μg dose test.³ Dorin et al,⁴ in a meta-analysis of the diagnosis of adrenocortical insufficiency that included more than 30 studies, found similar sensitivity and specificity in primary and secondary adrenal insufficiency comparing the 250-μg dose vs the low dose. In cases of mild primary adrenal failure, the low-dose test has better performance. A previous investigation in our research center contrasting 250 μg vs 10 μg proved that 10 μg had a better sensitivity than the standard dose, with excellent reproducibility and interchangeability.⁵ Similar findings have been shown by other authors contrasting 1 μg vs 250 μg of cosyntropin.⁶

We believe that the limited use of the low-dose cosyntropin test is not a matter of acceptance or performance but a consequence of the lack of vials containing lower doses of cosyntropin (1 to 10 μg), which makes this test technically challenging.^2,4 The steps needed for one-dose testing and the preservation time of the preparation are strong limitations to its wide use in clinical practice and endocrine laboratories.