Changes in High Resolution peripheral Quantitative Computed Tomography (HR-pQCT) in teenagers undergoing a first renal transplantation between baseline and 6 months

Abstract

Abstract Background Mineral bone disorders associated to chronic kidney disease (CKD-MBD) frequently persist after renal transplantation (R-Tx), being due to pre-existing CKD-MBD, immunosuppressive therapies and post-Tx hypophosphatemia. We aimed to evaluate bone biomarkers and microarchitecture at the time of and 6 months after R-Tx. Methods Here we present the single-center sub-group of patients included between 10 and 18 years of age from the prospective TRANSOS study (NCT02729142). Patients undergoing a first R-Tx were matched on a 1:2 basis on gender, puberty and age with healthy controls (HC) from the VITADOS cohort. Results are presented as median (Q1-Q3). Non-parametric tests were performed. Results At a median age of 15 (13-16) years, 19 patients (6 girls, 7 pre-emptive R-Tx, 7 steroid-sparing immunosuppressive strategies) underwent a first R-Tx, with PTH levels of 1.9 (1.4-2.9) the upper limit of normal (ULN). When comparing HC and patients at the time of R-Tx, bone parameters assessed with High Resolution peripheral Quantitative Computed Tomography (HR-pQCT) were significantly better in patients. Six months after R-Tx, patients displayed significantly impaired trabecular parameters at radius compared to baseline; results were not different at the weight-bearing tibia, neither cortical parameters at both sides. Six months after R-Tx, 6 (31%) patients displayed acidosis, 10 (53%) persistent hyperparathyroidism (always < 2 ULN) and 5 (26%) increased FGF23 levels; 11 (58%) received phosphate supplementation. Conclusion Data on bone health in teenagers receiving a first R-Tx seem reassuring, but radial trabecular bone microarchitecture impairment observed 6 months post-Tx may reflect subtle albeit present post-Tx CKD-MBD.