Kidney Week

Abstract: FR-PO274

Effects of Acute Administration of Ergocalciferol on Vitamin D Catabolism in Hemodialysis Patients

Session Information

• Mineral Disease: Vitamin D, PTH, FGF23
  November 03, 2017 | Location: Hall H, Morial Convention Center
  Abstract Time: 10:00 AM - 10:00 AM

Category: Mineral Disease

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

Authors

• Sirimongkolchaiyakul, Ornatcha, David Geffen School of Medicine at UCLA, Los Angeles, California, United States

Ornatcha Sirimongkolchaiyakul,

• Berg, Anders H., None, Boston, Massachusetts, United States

Anders H. Berg,

• Karumanchi, S. Ananth, Beth Israel Deaconess Medical Ctr/Harvard Medical School, Boston, Massachusetts, United States

S. Ananth Karumanchi,

• Wesseling-Perry, Katherine, David Geffen School of Medicine at UCLA, Los Angeles, California, United States

Katherine Wesseling-Perry,

• Thadhani, Ravi I., Massachusetts General Hospital, Boston, Massachusetts, United States

Ravi I. Thadhani,

• Salusky, Isidro B., Mattel Children's Hospital, Los Angeles, California, United States

Isidro B. Salusky,

Background

Vitamin D deficiency is highly prevalent in dialysis patients and D supplementation has been recommended. However, there is limited data of vitamin D catabolism in advanced CKD. Stimulation of 24-hydroxylase mediated catabolism of vitamin D metabolites may reduce serum 25(OH)D and 1, 25(OH)₂D levels. To test this possibility, we assessed vitamin D catabolism after a single ergocalciferol administration (D2) in hemodialysis patients (HD) and healthy volunteers (HV).

Methods

All subjects ingested a single oral dose of 50,000 IU ergocalciferol, HD patients aged 65.8 (20.6, 71.0) years (n = 35) and HV aged 41.0 (29.0, 62.0) years (n = 7). Biochemical determinations of 25D, 1,25D, 24,25 D and DBP were measured at baseline and 2-5 days after D₂ ingestion. Biochemical markers at baseline and post-therapy were compared.

Results

Concentrations of 25D₂ increased after D₂ in both HD and HV (average increases of +14.5 ng/mL [95%CI 9.5-29.4] and +21.2 [95%CI 14.6-29.8], respectively). Although average pre-treatment 25D₃ concentrations were significantly higher in HD compared to HV (21.2 ng/mL [95% CI 14.6-29.8] vs. 14.5 ng/mL [95%CI 9.5-29.4], p<0.05), concentrations of 24,25D3 were lower in HD (5.5 ng/mL [95% CI 3.5-15.6] vs. 14.5 ng/mL [95%CI 9.5-29.4], p<0.05). Average concentrations of 1,25D₃ was also lower in HD (4.7 pg/mL [95% CI 2.8-8.4] vs. 54.1 pg/mL [95%CI 47.7-69.2], p<0.05). Amongst HV, concentrations of 25D₃ decreased on average by -0.6 ng/mL [95%CI -3.9 to -0.2] after Vitamin D₂ administration, and 1,25D₃ decreased by -10.6 pg/mL(95%CI -20.2 to -0.5), whereas there was no significant decrease in 24,25D₃. Amongst HD, no significant changes in 25D₃, 24,25D₃, or 1,25D₃ were seen. Amongst HV, concentrations of both 1,25D₃ and 24,25D₃ correlated strongly with 25D₃ (R² = 0.4558 and R² = 0.6993, respectively). In contrast, the correlations between 25D₃ and 1,25D₃ and between 25D₃ and 24,25D₃ in HD were weaker (R² = 0.1285 and R² = 0.4654, respectively).

Conclusion

CKD is associated with higher 25D₃ but lower 24,25D and 1,25D concentrations, and 1,25 levels are more closely associated with 24,25D than with 25D in ESKD. Feedback regulation of both 1,25D and 24,25D by PTH and/or FGF23 in HD warrants further investigation.

Funding

• NIDDK Support