Clearance of 25-hydroxyvitamin D in Chronic Kidney Disease

Clearance of 25-hydroxyvitamin D in Chronic Kidney Disease

The goal of this study is to better understand vitamin D catabolism and how it is affected by CKD and race.

Specifically, the study team will evaluate the metabolic clearance of 25-hydroxyvitamin D3 in individuals with varying degrees of CKD and among participants who self-report race as Caucasian, African American or African. The long-term goal of this work is to enhance the clinical evaluation and treatment of impaired vitamin D metabolism.

Inclusion Criteria:

• Age ≥ 18 years

• Self-reported race Caucasian, African American, or African

• Serum total 25(OH)D 10-50 ng/mL

• Estimated GFR:

  • 60 mL/min/1.73m2 (N=40) 15-45 mL/min/1.73m2 (N=40) <15 mL/min/1.73m2, treated with hemodialysis (N=40)

Exclusion Criteria:

• Primary hyperparathyroidism
• Gastric bypass
• Tuberculosis or sarcoidosis
• Current pregnancy
• Child-Pugh Class B or C cirrhosis (i.e. cirrhosis with ascites, hepatic encephalopathy, bilirubin >=2 mg/dL, serum albumin <=3.5 g/dL, or PT >= 4 seconds)
• Use of vitamin D3, or vitamin D2 supplements exceeding a mean daily dose of 400 IU, within 3 months (wash-out allowed)
• Use of 1,25(OH)2D3 or an analogue, calcimimetics, or medications known to induce CYP24A1 within 4 weeks (wash-out allowed)
• Serum calcium > 10.1 mg/dL
• Hemoglobin < 10 g/dL