[The excretion of free cortisol in the urine in healthy children and in asthmatics treated with long-term inhaled glucocorticoids].

OBJECTIVE

To assess urinary free cortisol (UFC) excretion in 24 hour urine samples collected from asthmatic children treated with inhaled glucocorticoids (IGC).

PATIENTS AND METHODS

A retrospective cohort study was performed on a group of 358 children between the ages of 3 and 14 years. The children were divided into two groups, a normal population (n = 108) and an asthma group (n = 250). These children were treated uninterruptedly with IGC (mean dose 676 micrograms/day) during 17 +/- 8 months with budesonide (n = 221) or beclomethasone (n = 29) in dry powder (n = 167) or MDI with spacer chamber (n = 83). We considered the 24 hour urine sample valid when creatinine levels in blood and urine, as well as creatinine clearance, were normal. We determined UFC with a specific direct radioimmunoassay after cortisol extraction with dichloromethane. We performed a short ACTH test to assess the subnormal adrenocortical function when UC excretion in AG was less than -1SD.

RESULTS

UFC excretion was 81.98 +/- 32.12 nmol/m2/day in the asthma group. There was no correlation between UFC and the mean dose of IGC, total dose given, device used for inhalation, time of treatment or oral glucocorticoid series. The subgroup treated with beclomethasone presented UF rates lower than the subgroup treated with budesonide. Except for two cases, the ACTH test performed in the AG had normal adrenocortical responses.

CONCLUSION

1. We established the normal values for UFC excretion in our pediatric population. 2) The long term asthma treatment with glucocorticoids at mean doses of 650 micrograms l/m2/day decrease physiologically the UFC excretion since the adrenocortical response remains within the normal range.