Abstract
BACKGROUND: Recent reports have suggested short-term changes in serum parameters of bone metabolism with inhaled corticosteroids. The relevance of these findings to the balance between bone formation and resorption during years of corticosteroid treatment remains uncertain. METHODS: Two novel markers of bone turnover were first compared with conventional markers in a pilot study and subsequently measured in a long-term double blind study of inhaled corticosteroids. In study I 15 patients were newly started on at least 800 micrograms inhaled corticosteroids daily. At entry and after four weeks serum levels of alkaline phosphatase, osteocalcin, and PICP (procollagen type I carboxy terminal propeptide; a procollagen splice product) were measured as markers of bone formation, as well as the urinary hydroxyproline/creatinine ratio and serum levels of ICTP (type I collagen carboxy terminal telopeptide; a collagen degradation product) as markers of bone resorption. In study II 70 patients with airways obstruction received 800 micrograms beclomethasone daily in addition to terbutaline and 85 received bronchodilators only in a double blind fashion. Serum levels of PICP and ICTP were measured before and after 2.5 years of treatment. RESULTS: In study I a decrease in osteocalcin levels was accompanied by an increase in levels of PICP and a small and non-significant rise in alkaline phosphatase. There were no changes in hydroxyproline or ICTP. In study II no differences were found in serum levels of PICP between the treatment groups; an increase in serum ICTP was found in the group treated without inhaled corticosteroids compared with the group treated with inhaled corticosteroids. CONCLUSIONS: No detrimental long-term effect of inhaled corticosteroids was found with three conventional and two novel parameters of bone metabolism. The results indicate that long-term changes in bone turnover during treatment with inhaled corticosteroids should not be deduced from short-term studies with single serum parameters of bone metabolism, but well designed long-term studies of, for example, bone densitometry should be awaited before quoting detrimental effects of inhaled corticosteroids on bone metabolism.