Serum phosphate levels modify the impact of parathyroid hormone levels on renal outcomes in kidney transplant recipients

Sci Rep. 2020 Aug 13;10(1):13766. doi: 10.1038/s41598-020-70709-4.

Abstract

Separate assessment of mineral bone disorder (MBD) parameters including calcium, phosphate, parathyroid hormone (PTH), fibroblast growth factor 23 (FGF23), 25-hydroxyvitamin D, and 1,25-dihydroxyvitamin D (1,25D) predict renal outcomes in kidney transplant recipients (KTRs), with conflicting results. To date, data simultaneously evaluating these parameters and interwoven relations on renal outcomes are scarce. We conducted a prospective long-term follow-up cohort study included 263 KTRs with grafts functioning at least 1 year after transplantation. The outcome was a composite of estimated GFR halving and graft loss. Cox regression analyses were employed to evaluate associations between a panel of six MBD parameters and renal outcomes. The outcome occurred in 98 KTRs during a median follow-up of 10.7 years. In a multivariate Cox analysis, intact PTH (iPTH), phosphate, and 1,25D levels were associated with the outcome (hazard ratio, 1.60 per log scale; 95% confidence interval, 1.19-2.14, 1.60 per mg/dL; 1.14-2.23 and 0.82 per 10 pg/mL; 0.68-0.99, respectively). Competing risk analysis with death as a competing event yielded a similar result. After stratification into four groups by iPTH and phosphate medians, high risks associated with high iPTH was not observed in KTRs with low phosphate levels (P-interaction < 0.1). Only KTRs not receiving active vitamin D, poor 1,25D status predicted the worse outcome (P-interaction < 0.1). High iPTH, phosphate, and low 1,25D, but not FGF23, levels predicted poor renal outcomes. Simultaneous evaluation of PTH and phosphate levels may provide additional information regarding renal allograft prognosis.

Publication types

  • Observational Study

MeSH terms

  • Adult
  • Chronic Kidney Disease-Mineral and Bone Disorder / blood
  • Chronic Kidney Disease-Mineral and Bone Disorder / diagnosis
  • Chronic Kidney Disease-Mineral and Bone Disorder / prevention & control*
  • Female
  • Fibroblast Growth Factor-23
  • Fibroblast Growth Factors / blood
  • Follow-Up Studies
  • Graft Survival / physiology*
  • Humans
  • Kidney / pathology
  • Kidney / surgery
  • Kidney Transplantation / adverse effects*
  • Male
  • Middle Aged
  • Parathyroid Hormone / blood*
  • Phosphates / blood*
  • Prospective Studies
  • Renal Replacement Therapy / adverse effects
  • Transplant Recipients
  • Vitamin D / analogs & derivatives*
  • Vitamin D / blood

Substances

  • FGF23 protein, human
  • Parathyroid Hormone
  • Phosphates
  • Vitamin D
  • Fibroblast Growth Factors
  • Fibroblast Growth Factor-23
  • 25-hydroxyvitamin D