EFFECTS OF SHORT-TERM AND LONG-TERM TREATMENT WITH INHALED CORTICOSTEROIDS ON BONE METABOLISM IN PATIENTS WITH AIRWAYS OBSTRUCTION

Background - Recent reports have suggested short term changes in serum parameters of bone metabolism with inhaled corticosteroids. The relev ance of these findings to the balance between bone formation and resor ption during years of corticosteroid treatment remains uncertain. Meth ods - Two novel markers of bone turnover were first compared with conv entional markers in a pilot study and subsequently measured in a long term double blind study of inhaled corticosteroids. In study I 15 pati ents were newly started on at least 800 mu g inhaled corticosteroids d aily. At entry and after four weeks serum levels of alkaline phosphata se, osteocalcin, and PICP (procollagen type I carboxy terminal propept ide; a procollagen splice product) were measured as markers of bone fo rmation, as well as the urinary hydroxyproline/creatinine ratio and se rum levels of ICTP (type I collagen carboxy terminal telo-peptide; a c ollagen degradation product) as markers of bone resorption. In study I I 70 patients with airways obstruction received 800 mu g beclomethason e daily in addition to terbutaline and 85 received bronchodilators onl y in a double blind fashion. Serum levels of PICP and ICTP were measur ed before and after 2.5 years of treatment. Results - In study I a dec rease in osteocalcin levels was accompanied by an increase in levels o f PICP and a small and non-significant rise in alkaline phosphatase. T here were no changes in hydroxyproline or ICTP. In study II no differe nces were found in serum levels of PICP between the treatment groups; an increase in serum ICTP was found in the group treated without inhal ed corticosteroids compared with the group treated with inhaled cortic osteroids. Conclusions - No detrimental long term effect of inhaled co rticosteroids was found with three conventional and two novel paramete rs 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 bo ne metabolism, but well designed long term studies of, for example, bo ne densitometry should be awaited before quoting detrimental effects o f inhaled corticosteroids on bone metabolism.