Changes in bone turnover markers after discontinuing long-term glucocorticoid administration in children with idiopathic nephrotic syndrome: a multicenter retrospective observational study

Glucocorticoids affect bone turnover. Little is known about how bone turnover changes when glucocorticoids are discontinued following long-term administration. This retrospective observational study was conducted on the relationship between discontinuation of long-term administration of glucocorticoid and bone turnover markers (BTMs) in patients with childhood-onset idiopathic nephrotic syndrome. Serum bone alkaline phosphatase (BAP), intact procollagen type 1 N-terminal propeptide (P1NP), and tartrate-resistant acid phosphatase-5b (TRACP-5b) were evaluated as BTMs. Thirty-eight pairs of BTMs at glucocorticoid administration and after discontinuation were analyzed in 29 patients. The median age at baseline was 12.4 (interquartile range, 9.0–14.5) years, and the median time from the onset of nephrotic syndrome was 5.9 (3.3–9.7) years. The mean period from prednisolone discontinuation to the measurement of BTMs after glucocorticoid discontinuation was 3.5 ± 1.0 months. Changes in BTMs after glucocorticoid discontinuation were modest when the daily prednisolone dose was < 0.25 mg/kg/day (ln BAP standard deviation [SD] score, p = 0.19; log intact P1NP SD score, p = 0.70; TRACP-5b, p = 0.95). When the daily prednisolone dose was ≥ 0.25 mg/kg/day, all BTMs increased significantly after glucocorticoid discontinuation (ln BAP SD score, p < 0.01; log intact P1NP SD score, p < 0.01; TRACP-5b, p < 0.01). Decreased BTMs can rise within a few months of discontinuing long-term glucocorticoid administration. When the administered glucocorticoid dose is low, changes in BTMs may be small.