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Is there a link between vitamin D status and kidney transplant outcome?

Renal transplantation is now a common procedure. End-stage renal disease is the reason for kidney transplantation. Causes of end-stage renal disease include untreated hypertension, infections, diabetes mellitus, and other rarer conditions. Diabetes accounts for one fourth of transplants. The majority of recipients are on dialysis at the time of surgery.

About one in three donors are living and give one of their kidneys away. A typical recipient will live up to 15 years longer after a kidney transplant than they would have if kept on dialysis alone. Transplant tourism is not uncommon, where recipients go to an undeveloped country to buy a kidney from a poverty stricken donor.

Few people know that kidney function or glomerular filtration rate (GFR) is highly seasonal with wintertime impairment and summertime improvements.

Masugata H et al. Seasonal variation in estimated glomerular filtration rate based on serum creatinine levels in hypertensive patients. Tohoku J Exp Med. 2011;224(2):137-42.

This month, Doctor Frank Bienaimé, working under senior author Professor Dominique Prié of the Université Paris Descartes in France looked at renal transplantation and vitamin D levels.

Bienaimé F, Girard D, Anglicheau D, Canaud G, Souberbielle JC, Kreis H, Noël LH, Friedlander G, Elie C, Legendre C, Prié D. Vitamin D Status and Outcomes After Renal Transplantation. J Am Soc Nephrol. 2013 Mar 28.

They studied 634 kidney recipients between January 2005 and June 2010. They measured 25(OH)D levels three months after surgery and followed the patients for an average of 4 years. Mean vitamin D levels at 3 months were low, 13 ng/ml, and less than 30 ng/ml in 92% of patients.

The authors found no association between 25(OH)D and survival or transplant rejections, but they did find significant independent associations of lower 25(OH)D levels with lower measured GFR at 12 months (P=0.001) and higher risk for interstitial fibrosis and tubular atrophy (P=0.01). To my knowledge, this was the first study to link vitamin D status with functional renal outcomes in such patients.

The authors concluded:

“Studies from our group and others have already shown that cholecalciferol supplementation is a safe way to increase 25 (OH)D concentrations in kidney transplant recipients, but the small number of treated patients included in these studies and their short follow-up do not allow any conclusion on the effect of these treatments on kidney function. Our results should encourage randomized controlled trials evaluating the effect of early cholecalciferol supplementation on renal allograft function and provide valuable information on the magnitude of the expected effects of such treatments on renal function and histologic features.”