Bloodspot cortisol in mild asthma: the effect of inhaled corticosteroids.

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Abstract
Bloodspot cortisol, where finger pricked blood is applied to blotting paper, is suitable for repeated measurements in the home environment. The use of bloodspot cortisol measurements in children with asthma and the effect of inhaled corticosteroids on daytime cortisol concentrations were assessed. Twenty children with mild asthma were randomised to receive double blind either placebo or beclomethasone dipropionate 200 micrograms twice daily. Blood was taken by finger prick at home on waking, and treatment administered. Blood was then taken one hour after treatment, at lunchtime, and in the evening. The area under the curve (AUC) for the four time points was calculated as a composite index of daytime cortisol. Mean (SEM) bloodspot cortisols fell progressively over the day from 199.2 (15.6) nmol/l to 58.4 (8.9) nmol/l. Cortisol in the group treated with beclomethasone dipropionate was lower at all time points, but was significant only after treatment (mean (SEM) 120.9 (14.3) v 177.5 (21.0) nmol/l) and at lunchtime (mean (SEM) 82.7 (12.4) v 128.9 (12.6) nmol/l). AUC for the beclomethasone dipropionate treated group was also significantly decreased (mean (SEM) 317 (31.4) v 446 (29.7)). Beclomethasone dipropionate at a dose of 400 micrograms/day significantly suppresses the daytime cortisol profile.