Comparison of two different vitamin D supplementation regimens with oral calcifediol in kidney transplant patients

Abstract

Introduction: Vitamin D deficiency is prevalent in kidney transplant recipients (KTR) and recommendations on how to replenish vitamin D deposits are scarce.

Aim: To evaluate, in KTR, the safety and efficacy of calcifediol in two different vitamin D supplementation regimens, in order to assess the most suitable dose.

Patients and methods: Prospective observational study with two calcifediol supplementation regimens randomly prescribed by clinicians in liquid form, at 266 mcg doses, monthly or biweekly. We analyzed 168 KTR with a functioning allograft for more than 6 months. Patients receiving other vitamin D forms, calcimimetics or bisphosphonates were excluded. Before calcifediol initiation (pre-treatment levels) and after at least 3 months of treatment (post-treatment levels), we measured serum levels of 25-OH vitamin D (25(OH)D), parathyroid hormone (PTH), alkaline phosphatase (ALP), calcium (sCa), phosphate (sPO4) and creatinine (sCreat).

Results: In the monthly group (n = 72), 25(OH)D levels increased from 14 ng/ml [interquartile range, IQR 9-22] at baseline to 31 [20-38] (p = 0.000), PTH decreased from 124 pg/ml [87-172] to 114 [78-163] (p = 0.006), while sCa and sPO4 remained stable. In the biweekly group (n = 96), 25(OH)D increased from 14 ng/ml [9-20] at baseline to 39 [28-52] (p = 0), PTH decreased from 141 pg/ml [95-221] to 112 [90-180] (p = 0.000), sCa remained stable and sPO4 increased from 3.3 ± 0.6 mg/dl to 3.5 ± 0.6 (p = 0.003). Renal function remained stable in both groups.

Conclusion: Vitamin D reposition with oral calcifediol, in a biweekly or monthly regimen, is safe and effective in improving 25(OH)D blood levels and in decreasing PTH in kidney transplant recipients.

Keywords: Calcifediol; Kidney transplant; Parathyroid hormone; Vitamin D.