The Effect of Short-Term Vitamin D Supplementation on Calcium Status in Vitamin D Insufficient Renal Transplant Recipients at Risk of Hypercalcemia

Abstract

Insufficient Renal Transplant Recipients at risk of Hypercalcaemia. Objective: Vitamin D insufficiency is highly prevalent amongst renal transplant recipients and in observational studies is associated with adverse outcomes. Hypercalcaemia, usually due to persistent hyperparathyroidism, also commonly occurs in this population and often coexists with vitamin D insufficiency. However, concern that vitamin D supplementation might exacerbate the pre-existing hypercalcaemia often leads clinicians to avoid vitamin D supplementation in such patients. This feasibility study aimed to quantify the effect on serum calcium of short-term lowdose cholecalciferol supplementation in a group of renal transplant recipients with a recent history of serum calcium levels >10 mg/dL. Design: This was a two-week, single arm, open-label trial. Setting: Renal transplant follow-up clinic in an Irish University Hospital. Subjects: 18 vitamin D insufficient adult patients with a functioning renal allograft (eGFR > 30 ml/min/1.73m 2) and a recent history of serum calcium>10mg/dL. Intervention: Two weeks of treatment with 1000 IU cholecalciferol/day. Main Outcome Measure: Change in plasma ionized calcium and urine calcium:creatinine ratio at follow-up as compared to baseline. Results: The mean (sd) baseline 25 (OH) vitamin D (25 (OH) D) concentration was 15.9 (5.97) ng/mL and the mean (sd) baseline serum calcium was 10.50 (0.6) mg/dL. Following the 2-week intervention, median (IQR) change in serum calcium from baseline to follow-up was-0.08 (-3.6 to 0.08) mg/dL, p=0.3. Mean (sd) ionized calcium decreased from 5.24 (0.32) mg/dL at baseline 4 to 5.16 (0.28) mg/dL, p= 0.05. The median (IQR) change in the urinary calcium:creatinine ratio was 0.001 (-0.026 to 0.299) mg/mg, p=0.88. The median (IQR) change in 25 (OH) D was 3.6 (2.9 to 6.2) ng/mL, p<0.05. Conclusions: In vitamin D insufficient renal transplant recipients at risk of hypercalcaemia, lowdose short-term oral cholecalciferol supplementation improves 25 (OH) D concentrations without exacerbating hypercalcaemia or increasing the urinary calcium:creatinine ratio.

Vitamin D intake and status in Ireland: a narrative review

“…This is similar to the findings of a global meta-analysis, which identified that disease severity was associated with lower vitamin D status (173) . Prevalence of levels <50 nM/l was also high in renal patients (69 %) (174) and those who had thyroidectomy (75 %) (175) . Between 35 and 50 % of Irish asthmatic children had vitamin D levels <50 nM/l (176,177) , in keeping with a recent global meta-analysis (178) .…”