The researchers found five-year kidney survival was 75% in patients with vitamin D levels of more than 50 nanomoles per litre (nMol/L) at the start of the study and 50% in those with levels below this.
Renal survival increased 8.2% per 10 nmol/L increase in vitamin D. Vitamin D deficiency was higher in children with chronic kidney disease since one function of the organ was to produce the active form of the vitamin.
The researchers said supplementation could help. “Vitamin D is an effective, easily available, safe and cheap nutritional supplement that may be a useful adjunctive treatment to renin-angiotensin-aldosterone system (RAAS) blockade to retard progressive renal function decline.”
Blocking the RAAS, the hormone system that regulated blood pressure and fluid balance, has been shown to speed up the progression of chronic kidney disease. Angiotensin-converting enzyme inhibitors (ACEi) have been routinely used to slow the diseases progression in this way, although there is no absolute cure for the condition.
This latest paper looked at the possible impact of vitamin D, which was thought to suppress renin transcription. The researchers said this “cross-talk” between the RAAS and vitamin D pathways suggested modulation of one system could have positive effects on the other.
The study measured these factors in 167 children with the condition at baseline and after eight months. The average age of the children was 11.4 years.
The researchers came from the Great Ormond Street Hospital for Children in the UK, Gaslini Institute in Italy, the Children’s Memorial Health Institute in Poland, the Ospedale Pediatrico Bambino Gesù in Italy, Cukurova University School of Medicine in Turkey, Semmelweis University Budapest in Hungary, Hacettepe University Faculty of Medicine in Turkey, Medical University of Gdansk in Poland, Vilnius University Paediatric Center in Lithuania, Unit of Pediatric Nephrology and Dialysis in Italy, Hopital Necker in France and University of Heidelberg in Germany.
The UK's National Health Service estimated that about one in five men and one in four women between the ages of 65 and 74 had some degree of chronic kidney disease. The risk of having some degree of kidney disease increases with age.
Source: Journal of the American Society of Nephrology
Published online ahead of print,doi:10.1681/ASN.2014090947
“Normal 25-hydroxyvitamin D levels are associated with less proteinuria and attenuate renal failure progression in children with chronic kidney disease”
Authors: R. Shroff, H. Aitkenhead, N. Costa, A. Trivelli, M. Litwin, S. Picca, A. Anarat, P. Sallay, F. Ozaltin, A. Zurowska, A. Jankauskiene, G. Montini, M. Charbit, F. Schaefer and E. Wuhl