Changes in Vitamin D Biomarkers According to the Cause-Glomerular Filtration Rate Albuminuria Classification in Patients with Chronic Kidney Disease

Abstract

Background Monitoring the vitamin D status is vital for managing mineral and bone disorders (MBDs) in patients with chronic kidney disease (CKD). The CKD classification based on cause of CKD, glomerular filtration rate (GFR), and albuminuria (CGA) is crucial for managing patients with CKD, yet no study has explored their association with various vitamin D biomarkers. Our study aims to investigate changes in vitamin D biomarkers based on CKD cause, estimated GFR (eGFR), and albuminuria levels. Methods We prospectively analyzed blood and urine samples from 206 patients with CKD stages G2–G5. After classifying each group according to the presence or absence of diabetes, eGFR, and severity of albuminuria, the differences in various vitamin D biomarkers in each group were compared. Results Among patients with diabetic kidney disease, those with diabetic nephropathy showed significantly lower levels of 24,25(OH)2D and bioavailable 25(OH)D compared to those without. When classified according to eGFR, patients with a low eGFR had significantly lower mean levels of 24,25(OH)2D and VMR, but the change in all 25(OH)D markers was not significant. In patients with diabetes, all 25(OH)D markers significantly decreased as albuminuria worsened, whereas in patients without diabetes, only bioavailable 25(OH)D showed a significant association with albuminuria. Conclusions Changes in vitamin D markers differed according to the CGA classification. However, as was a small-scale study, large-scale studies with a longer follow-up are necessary.