Impact of Vitamin D Therapies on Chronic Kidney Disease

Vitamin D helps form and strengthens bones by allowing the body to absorb calcium. Vitamin D
helps the immune system fight infection as well as helps keep muscles strong. Without enough
vitamin D, bones can become weak, thin and brittle.

Vitamin D is useful in people with all different types of health issues. CKD is the slow
loss of kidney function over time. The main function of the kidneys is to remove wastes and
excess water from the body. This loss of function usually takes months or years to occur
Patients with CKD often have low levels of vitamin D in their blood.

This study will have two groups of patients with CKD and one group of patients that have
normal kidney function, but all groups will have low levels of vitamin D. The two groups
with CKD (group 1 and group 2) will receive either cholecalciferol or calcitriol. The
purpose of having a control group (group 3) without CKD will be to evaluate if any changes
that are witnessed in response to vitamin D therapy are specific to patients with kidney
disease or apply to all patients with vitamin D deficiency who receive vitamin D
supplements.

There are two different drugs in this study. One is called Calcitriol and is approved by the
Food and Drug Administration (FDA) as a vitamin D supplement. The other drug is called
cholecalciferol and it is approved by the FDA. Unlike calcitriol, cholecalciferol is a
nutritional form of vitamin D that can often be found in various types of foods and its
chemical structure must be changed by the body to become the active form of vitamin D. It is
believed that cholecalciferol may have different effects in the body compared to calcitriol.
It is possible that CKD patients would benefit from receiving both of these drugs, but this
is currently unclear. While on this study you will receive either one of these study drugs,
depending on which group you are assigned to.

Inclusion Criteria:

- Chronic kidney disease w/GFR<35ml/min

- Nutritional vitamin D deficiency, defined as 25(OH)D < 25ng/ml

- Secondary hyperparathyroidism, PTH>75pg/mL

Exclusion Criteria:

- Active infection

- Recent hospitalization for acute illness (within last month)

- Refusal to study participation

- History of chronic inflammatory disease process (i.e. inflammatory bowel, rheumatoid
arthritis, SLE, etc.)

- Allergy to cholecalciferol or calcitriol

- History of parathyroidectomy

- Functional renal transplant within 5 years

- Current treatment with immunosuppressant medications

- Noncompliance with prescribed medications