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Vitamin D supplementation will not extend hypercalcemia in patients with kidney transplants
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A small study conducted by researchers in Ireland shows use of Vitamin D supplementation among patients with a kidney transplant does not worsen cases of hypercalcemia.
Persistent hyperparathyroidism, common among transplant patients, often leads to hypercalcemia and “often co-exists with vitamin D insufficiency,” Irene Lynch Cronin, BSc, of the department of clinical nutrition and dietetics at Cork University Hospital, and colleagues wrote. “However, concern that vitamin D supplementation might exacerbate the pre-existing hypercalcemia often leads clinicians to avoid vitamin D supplementation in such patients.”
The high prevalence of vitamin D insufficiency (up to 94%, the authors noted) among renal transplant patients is “partly due to recommendations to minimize sun exposure and advising use of sunscreens with a high sun protection factor (SPF) due to increased risk of skin cancer among the renal transplant population, inadequate nutritional vitamin D supplementation both during dialysis and after transplantation, and an increased vitamin D catabolism due to immunosuppressive drugs,” the authors wrote.
The researchers conducted the 2-week, single arm, open-label trial among 18 patients with vitamin D-deficiency with a kidney transplant and a recent history of serum calcium levels of 0.10 mg/dL to determine the effect of short-term, low-dose cholecalciferol supplementation on serum calcium. Patients were given 1,000 IUs of cholecalciferol per day.
Patients in the study had a mean baseline vitamin D concentration of 15.9 (5.97) ng/mL and a mean baseline serum calcium of 10.50 (0.6) mg/dL. Following the 2-week intervention of supplemental vitamin D, median change in serum calcium from baseline to follow-up was 20.08 (23.6 to 0.08) mg/dL.
“There was no substantial change in FGF23 (median change: 21.9 RU/mL). The median (IQR) change in the urinary calcium: creatinine ratio was 0.001 (20.026 to 0.299) mg/mg, P = .88, which was not significant. Mean (standard deviation) baseline urine calcium: creatinine ratio was 0.16 (0.1) mg/mg which is below the threshold for hypercalciuria (.0.2 mg/mg).
“At baseline, PTH correlated with ionized calcium r = 0.69, P = .03. This was the only correlation of significance,” the authors wrote.
The authors acknowledged the size of the study created limitations, as well as the short duration of the intervention.
“Despite this, we see relatively uniform effects with some significant results being evident even in this small sample size,” the authors wrote. “Although the intervention period was not long enough to achieve adequate 25 (OH) D levels in all participants (dependent on their baseline 25 (OH) D levels), this initial safety study supports the feasibility and safety of conducting, with appropriate monitoring, a longer-term interventional trial to quantify the risks and benefits of vitamin D supplementation in this population, particularly in relation to calcium metabolism,” the authors wrote.
Disclosures: The authors report no relevant financial disclosures.
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