Pros and Cons of Vitamin D Supplementation

In a time where everyone seems to be supplementing vitamin D, it good to review the literature to assure ourselves we are doing the right thing. The NKF talk by Dr. Michal Melamed accomplished this perfectly. Here is an outline of her talk:

Vitamin D and PTH
Randomized controlled trials clearly show that activated vitamin D clearly decreases PTH in patients with CKD. 25 vitamin D has a smaller effect.

Vitamin D and Mortality
Observational data suggests that activated vitamin D supplementation results in better survival of dialysis patients. This seems to hold true even when patients have a high phosphorus level. Proper randomized controlled studies on this topic do not exist.

Vitamin D and CKD
Studies with KO mice suggest that lack of vitamin D results in high renin, angiotensin II, HTN and LVH. Vitamin D supplementation was found to lower blood pressure in African Americans without CKD.

Vitamin D and LVH
The PRIMO study (Thadhani, JAMA 2012) found no effect of paricalcitrol on LVH although it did decrease PTH.

Vitamin D – Can you have too much?
Dr. Barry Friedman found an association between vitamin D supplementation and calcified plaque in diabetics. The women’s health initiative study (largest vitamin D RCT ever), comparing vitamin D and calcium supplementation to placebo, did not show any treatment related reduction of CKD, mortality or cancer – although patients in the treatment arm had more kidney stones.

In summary: Vitamin D reduces PTH. Observational studies suggest reduced mortality with vitamin D supplementation. Studies do not suggest a decrease in LVH. Blindly supplementing dietary vitamin D without checking levels can lead to an increase risk of kidney stones.

Looks like there is still more work to be done! –by Dr. Vinay Nair, eAJKD Advisory Board member. 

Dr. Daniel Weiner, AJKD Deputy Editor, moderated the session on CKD management and had the following comments on this talk: Dr. Melamed from Albert Einstein gave a detailed review of nutritional and activated vitamin D, noting that, despite all of the attention paid to this topic, there remains uncertainty regarding how to proceed, with a lack of data on hard clinical outcomes in people with CKD.

Check out more eAJKD coverage of the NKF’s 2013 Spring Clinical Meetings!