Adrenal suppression by inhaled steroids is common

Inhaled steroids (glucocorticoids/corticosteroids) are commonly prescribed for asthma but their systemic effect is often overlooked. A clinical study just published in the European Journal of Endocrinology offers evidence that inhaled steroids such as fluticasone (Flovent®), budesonide (Pulmicort®), and beclomethasone (Qvar®) frequently cause serious adrenal suppression. They also show that simply measuring morning cortisol can help indicate whether adrenal insufficiency is occurring. The authors state:

"Up to 3% of US & UK populations are prescribed glucocorticoids (GC). Suppression of the hypothalamo-pituitary-adrenal axis with the potential risk of adrenal crisis is a recognized complication of therapy."

A better way to measure adrenal suppression due to inhaled steroids

The definitive test for adrenal failure or insufficiency due to autoimmunity (Addison's disease), oral or inhaled steroids is stimulate the adrenals with ACTH (adrenocorticotropic hormone, known as Synacthen.cosyntropin, and tetracosactide), then measure after 30 and 60 minutes the amount of cortisol produced. This is inconvenient and costly as a screening test for patients using inhaled steroids.

"The 250_g short Synacthen stimulation test (SST) is the most commonly used dynamic assessment to diagnose adrenal insufficiency. There are challenges to the use of the SST in routine clinical practice, including both the staff and time constraints and a significant recent increase in Synacthen cost."

So the authors investigated to determine whether measuring morning cortisol could be validated as a quicker and easier assessment.

"We performed a retrospective analysis to determine the prevalence of adrenal suppression due to prescribed GCs and the utility of a morning serum cortisol for rapid assessment of adrenal reserve in the routine clinical setting."

Inhaled steroids suppress adrenal function in a dose dependent manner

In their data 20% of patients on inhaled steroids had adrenal suppression as shown by Synacthen stimulation:

"2773 patients underwent 3603 SSTs in a large secondary/tertiary centre between 2008-2013 and 17.9% (n=496) failed the SST. Of 404 patients taking oral, topical, intranasal or inhaled GC therapy for non-endocrine conditions, 33.2% (n=134) had a subnormal SST response. In patients taking inhaled GCs, without additional GC therapy, 20.5% (34/166) failed an SST and suppression of adrenal function increased in a dose-dependent fashion."

Moreover, this did in fact correspond to the morning cortisol measurements:

"Using receiver operating characteristic curve analysis in patients currently taking inhaled GCs, a basal cortisol ≥348nmol/L provided 100% specificity for passing the SST; a cortisol value <34nmol/L had 100% sensitivity for SST failure. Using these cut-offs, 50% (n=83) of SSTs performed on patients prescribed inhaled GCs were unnecessary."

Clinical implications

Too often patients are left in the dark about the systemic effects of inhaled steroids. This helpful study reminds practitioners that there can be global adverse effects stemming from adrenal suppression with possible long-term consequences for case management of a wide variety of disorders; and that this can be screened by simply measuring morning cortisol. The authors conclude:

"Adrenal suppression due to GC treatment, particularly inhaled GCs, is common. A basal serum cortisol concentration has utility in helping determine, which patients should undergo dynamic assessment of adrenal function."