Insufficient vitamin D status may increase risk of kidney disease

Low blood vitamin D levels seem to increase the likelihood of developing protein in the urine, an early sign of kidney disease, reports a new Australian study.

The observational study measured serum 25-hydroxyvitamin D concentrations of more than 5,800 men and women (25 years or older) without protein in their urine at the beginning of the trial (1). After five years, 3.8% of the participants had the protein albumin in their urine, indicating that their kidneys had undergone some damage that prevented them from retaining protein in the body. Those participants with vitamin D deficiency (less than 15 nanograms of vitamin D per milliliter of blood) were found to be 70% more likely to have albuminuria.

The researchers commented that, although it is unknown whether vitamin D levels are a cause or a symptom of kidney damage, the findings could bolster the case for more careful vitamin D monitoring and using vita-min D levels to identify individuals who may be at risk for developing kidney disease. It would also be likely that patients with chronic conditions, such as chronic kidney disease, may need higher vitamin D levels than the general healthy population.

Two positive tests for albuminuria over several weeks are an early indication of kidney disease. For patients with diabetes and/or established chronic kidney disease, albuminuria is associated with more rapid progres-sion of their condition and a greater chance that kidney failure will develop.

1. Damasiewicz M. J. et al. Serum 25-hydroxyvitamin D deficiency and the 5-year incidence of CKD. American Journal of Kidney Diseases. 2013; 62(1):58-66.