Kidney Week

Abstract: FR-PO0738

Functional Vitamin D Markers Across Racial Groups in Pediatric CKD

Session Information

• Pediatric Nephrology: CKD, ESKD, and Glomerular Diseases
  November 07, 2025 | Location: Exhibit Hall, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Pediatric Nephrology

• 1900 Pediatric Nephrology

Authors

• Laster, Marciana, Indiana University School of Medicine, Indianapolis, Indiana, United States

Marciana Laster, MD, MS

• Matheson, Matthew, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland, United States

Matthew Matheson

• Ginsberg, Charles, University of San Diego, San Diego, California, United States

Charles Ginsberg, MD, MA

• Jerry-Fluker, Judith, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland, United States

Judith Jerry-Fluker

• Schwartz, George J., University of Rochester, Rochester, New York, United States

George J. Schwartz, MD

Background

The assessment of vitamin D status using routinely measured 25-OHD is complicated by its inconsistent association with fractures across racial groups. In the pediatric CKD population, we investigated the relationship between race and two functional markers of vitamin D status: the vitamin D metabolite ratio (VMR) and the vitamin D activation ratio.

Methods

Using data from the CKiD cohort, we identified 97 age-, CKD stage- and sex-matched children of non-Hispanic White (NHW) and non-Hispanic Black (NHB) race. LC-MS/MS was used to measure 25-OHD, 24,25-OH₂D and 1,25-OH₂D . The VMR was calculated as the ratio of 24,25-OH₂D to 25-OHD and the activation ratio was calculated as the ratio of 1,25-OH₂D to 25-OHD. Adjusted linear regression models were used to determine 1) the relationship between vitamin D markers and intact PTH and 2) the relationships between race and each marker of vitamin D status, separately.

Results

Cohort characteristics are listed in Table 1. Racial groups were well-matched. In an adjusted linear regression model, a 10% higher VMR was associated with a 5% lower intact PTH (Table 2). The activation ratio was not associated with PTH. In separate linear regression models with the VMR and the activation ratio as outcomes, NHB (vs. NHW) was associated with a 28.8% lower VMR and a 76.3% higher activation ratio (Table 3).

Conclusion

Similar to adult studies, the VMR and the vitamin D activation ratio differ by race. Given lower VMR is associated with fracture risk in prior studies, further studies are needed to determine if this is consistent in pediatric CKD. Because of the known decreased risk of fracture associated with NHB race, future studies are needed to investigate whether higher CYP27B1 activity, noted here, contributes to the known decreased fracture risk in NHB participants.

Funding

• NIDDK Support

Digital Object Identifier (DOI)

• doi: 10.1681/ASN.2025g4wg4j15