Vitamin D and Muscle Strength in the Dialysis Population

Vitamin D is necessary for healthy bones. Vitamin D is made in our skin when we are exposed to sunlight, but it is also found in foods that we eat and in vitamin pills. Low levels of vitamin D are common in many groups of people, because we do not get enough sun during the winter and because we eat few foods that have vitamin D in them. Some foods with vitamin D are salmon, mackerel, tuna, and fortified milk, which has had vitamin D added to it.

We know that nearly all kidney disease patients on dialysis do not have enough vitamin D in their bodies. We believe this condition can cause muscle weakness, leading to falls and broken bones. These are common problems for patients who are receiving dialysis. For example, dialysis patients have a much higher risk of hip fractures (broken hips). However, no formal research has been done on patients with low vitamin D levels receiving dialysis, to see if they actually have muscle weakness and related problems.

There are two goals of this study. First, we want to see if patients on dialysis who have low vitamin D levels are actually at risk for muscle weakness, muscle pain, and broken bones. We also want to find out if giving vitamin D pills to these patients will result in better muscle strength, less muscle pain, and fewer falls.

In this study, we will compare vitamin D to placebo. Placebo capsules look exactly like vitamin D capsules but contain no active ingredients. We use placebos in research studies to be sure that the study results are due to the study drug and not to other reasons.