Vitamin D in Kidney Disease

Chemical structure of cholecalciferol, aka vitamin D3. (Photo credit: Wikipedia)

photo credit: aluzano

The authors of a recent study in the clinical journal of the american society of nephrology has suggested that vitamin d may have a role in reducing proteinuria in chronic kidney disease. Previously the main stay of therapy for protein in the urine or proteinuria has been the use of a class of drugs known as A.C.E inhibitors (ACEI). This newly discovered effect of vitamin D occurs in addition to the effect of ACEI on proteinuria. This implies that vitamin D supplementation may be a possible adjunctive therapeutic option in patients with kidney disease and proteinuria. Vitamin D may also reduce the loss of a vital class of cell within the kidney, the ever more important podocyte. This cell class is involved multiple diseases affecting the kidneys ability to retain protein in the blood. Dysfunction of the podocyte has been cited as being responsible for some types of inherited causes of kidney failure. In addition blood pressure, the sensitivity of the body to insulin as well as inflammation are all improved by vitamin D.

The authors note that although only few studies exist, the data suggests that this is an area worthy of further research, with previous studies in pre-dialysis patients showing similar findings as above. The decrease in proteinuria due to vitamin D has also been shown to occur in patients with IgA nephropathy in one study of 10 patients, it was also accompanied by decreased levels of chemicals responsible for the development of scarring in the kidney. The development of fibrosis or scarring occurs as a final pathway of injury in many diseases that affect the kidney including diabetic kidney disease. Diabetic kidney disease is perhaps the most common cause of kidney failure requiring dialysis. As such if vitamin D supplementation should be able to have even a small impact on the survival of kidneys of patients with diabetic kidney disease the resultant decrease in spending on dialysis would save millions of US dollars each year.

Several mechanisms have been suggested for the positive action of vitamin D in kidney disease. Chief among these is the notion that the vitamin acts as a hormone at the level of specific tissues and organs of the body where it influences immunity, vascular function cardiac function and muscle function. It also acts on the immune system to turn off inflammation. These are all effects that would benefit patients with kidney disease.

These are truly interesting times for Vitamin D.