The effect of inhaled corticosteroids on the urinary calcium to creatinine ratio in childhood asthma

Background: The use of inhaled corticosteroids (ICS) via spacers in childhood asthma is increasing. However, concern has been raised about its long-term impact. Hypercalciuria is a known adverse effect of treatment with systemic corticosteroids. The urinary calcium to creatinine ratio (UCa: Cr) is a simple, reliable and non-invasive tool for evaluation of hypercalciuria. Aim: To determine whether ICS can induce hypercalciuria in children with asthma. Setting: Outpatient clinic in a referral hospital. Methods: The UCa : Cr was determined in 25 children aged 3-6 years with mild-to-moderate persistent asthma before and after a 2-month course of inhaled budesonide 400 mug/day via an aerochamber. Children who had received oral corticosteroids, diuretics, antibiotics or theophylline were excluded. Statistics: Paired Student's t-test and Fisher's exact test. Results: The mean UCa: Cr was similar in the children with asthma before and after 2 months' administration of budesonide (0.10 +/- 0.10 and 0.11 +/- 0.08, respectively; p = 0.601). The numbers of hypercalciuric children were two and five, respectively (p = 0.417). In 68% of patients, the UCa : Cr increased and in 16% the increase indicated hypercalciuria (UCa : Cr > 0.2). Conclusions: Although the treatment of childhood asthma with budesonide 400 mug/day via an aerochamber does not appear to be associated with hypercalciuria, the existence of a subgroup of patients in whom ICS may induce hypercalciuria is plausible. This needs to be further evaluated in a larger study.