SUN-LB093 Change in Bone Mineral Density over One Year Was Not Associated with FGF-23 in Patients New to Dialysis

Abstract

Background: FGF-23 is a phosphaturic factor as it inhibits renal phosphate reabsorption and vitamin D activation. FGF - 23 levels are elevated in hemodialysis patients irrespective of serum phosphate levels. No association was found between FGF - 23 and cortical bone mineral density (BMD) in individuals on long-term hemodialysis using DXA which is less sensitive than QCT. Here we reexamine the association using QCT in new to dialysis patients. Objective: To determine the relationship between FGF23 with BMD and change of BMD over one year in incident dialysis patients. Methods: Ninety-three individuals new to dialysis enrolled in this prospective study. Patients completed a baseline visit and one follow-up visit at least 12 months later. Detailed information regarding demographics, medical history, and medication usage was obtained by self-report. Specimens were collected for measurement of parathyroid hormone, phosphate, FGF-23, vitamin D, calcium and inflammatory markers at the baseline visit. Trabecular and cortical volumetric bone mineral density (BMD) and bone mineral content (BMC) were obtained by tibial quantitative CT scan (QCT) at the baseline and follow-up visits. Multivariable linear regression was used to assess the relationship between FGF23 and change in BMD over time. Results: The mean age of participants was 50.6 ± 13.2 years. A third of the cohort was women and 61% were AA. The dialysis vintage was 66 ± 31 days. The baseline median (IQR) for FGF-23 was 1238.4 (515.18 - 2217.8). The baseline Vitamin D was 22 (13.4-36.1 ) . Median change in cortical BMD Z-score was -0.43 (-0.74, -0.12). Change in BMD was associated with presence of diabetes (coeff (se) -0.37 (0.15) p=0.02), calcium (0.23 (0.08) p=0.01) and IL6 (coef 0.08 (0.02) p=0.002) but not with log FGF-23 (0.001 (0.08) p=0.99). Results were similar for African Americans and non-African Americans. Conclusions: Over one year of follow-up, incident dialysis patients had decreased cortical bone mineral density. However, the change in bone mineral density was associated with diabetes status, calcium and IL-6 but not associated with FGF-23 . Unless otherwise noted, all abstracts presented at ENDO are embargoed until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. s presented at a news conference are embargoed until the date and time of the news conference. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.