Can 11 beta-Hydroxysteroid Dehydrogenase Activity Predict the Sensitivity of Bone to Therapeutic Glucocorticoids in Inflammatory Bowel Disease?

In healthy individuals measures of 11 beta-hydroxysteroid dehydrogenase type 1 (11 beta-HSD1) enzyme activity predict the change in bone formation markers in response to therapeutic glucocorticoids. It is unclear whether these measures remain predictive in inflammatory disease. We therefore examined whether 11 beta-HSD1 activity predicts changes in bone markers and bone mineral density (BMD) in patients with inflammatory bowel disease (IBD) treated with therapeutic glucocorticoids. Prospective and cross-sectional studies were carried out in patients attending a gastroenterology clinic with active (n = 39) or clinically inactive (n = 34) IBD and healthy controls (n = 51). Urinary corticosteroid metabolite profiles were obtained on a spot urine sample and total corticosteroid metabolite excretion and 11 beta-HSD1 activity (measured as the ratio of tetrahydrocortisol to tetrahydrocortisone metabolites, [THF+alloTHF]/THE) determined. Patients with active disease were treated with an 8-week reducing course of oral prednisolone. The (THF+alloTHF)/THE ratio was significantly increased in patients with IBD, even those in clinical remission. The baseline (THF+alloTHF)/THE ratio failed to predict the decrease in bone formation markers or hip BMD. Measures of 11 beta-HSD activity do not predict bone loss during glucocorticoid treatment of active IBD, probably due to disease-related increases in 11 beta-HSD1 activity. Our observation of elevated 11 beta-HSD1 activity in clinically inactive IBD implicates gastrointestinal glucocorticoid activation in the maintenance of disease remission.