Abstract: FR-PO261

Ratios of Parathyroid Hormone, Fibroblast Growth Factor 23, and 1,25-Dihydroxylvitamin D and CKD Progression

Session Information

Category: Mineral Disease

  • 1202 Mineral Disease: Vitamin D, PTH, FGF-23

Authors

  • Levin, Adeera, UBC, Vancouver, British Columbia, Canada
  • Djurdjev, Ognjenka, BC Renal Agency, Vancouver, Alberta, Canada
  • Tang, Mila, St. Paul's Hospital, Vancouver, British Columbia, Canada
  • Zierold, Claudia, DiaSorin, Stillwater, Minnesota, United States
  • Blocki, Frank A., DiaSorin, Stillwater, Minnesota, United States
  • Bonelli, Fabrizio, DiaSorin, Stillwater, Minnesota, United States
  • Wolf, Myles S., Duke University, Durham, North Carolina, United States
Background

Patients with CKD experience variable rates of progression. Ratios of parathyroid hormone (PTH(1-84)), fibroblast growth factor 23 (FGF23) and 1,25-dihydroxylvitamin D (1,25(OH)2D) describing relative values of important hormonal systems and renal tubular function that provide insight into risk of CKD progression.

Methods

We examined data from CanPREDDICT, a prospective CKD pan-Canadian cohort from 2008-2013, followed biannually for 5yrs, with adjudicated outcomes. PTH(1-84), intact FGF23 and 1,25(OH)2D were evaluated at baseline using precise new assays (Diasorin Inc), on the LIAISON XL analyzer. We used Cox proportional hazards to examine composite renal events (CRE) defined by need for renal replacement therapy or 50% decline of baseline eGFR, adjusted for age, sex, BP, weight, eGFR, ACR, Alb, PO4, HCO3, Ca, Hgb and K+ (base). Univariate and multivariate adjusted HRs were calculated per one standard deviation increments using natural log-transformed variables where appropriate.

Results

The study cohort included 1784 pts with a median follow-up of 41 months; mean age of 68yrs; 62% males; and mean eGFR of 28 ml/min/1.73m2 (19% <20ml/min, 42% 20-29ml/min and 39% 30-45mil/min). There were 429 (24%) CRE. Higher PTH(1-84) and FGF23 levels, and lower 1,25(OH)2D and ratios of 1,25(OH)2D/PTH(1-84) and 1,25(OH)2D/FGF23 precited significantly higher risk of CRE in unadjusted and adjusted analyses [p<0.01; Figure 1a] . The corresponding category-free net reclassification indices [95%CI] were 13.5%[-0.2 to 32.3%], 6.2%[-8.1 to 22.9%], 6.2%[-11.4 to 26.9%], 17.6%[-1.7 to 34.4%], and 2.8%[-13.6 to 20.0%] respectively.

Conclusion

High levels of PTH(1-84) and FGF23 predict higher risk of CRE; higher levels of 1,25(OH)2D may be protective against CRE. The ratio of these may offer better insights than any one value alone. Further study of individual and combinations of biomarker levels is needed.

Funding

  • Commercial Support