Vitamin D Replacement After Kidney Transplant

This trial will assess the following aims:

1. Time to plateau vitamin D concentrations after initiating vitamin D supplements

2. Safety of vitamin D replacement based on serum and urine calcium

3. Effect of vitamin D on PTH concentration in individuals with elevated parathyroid
hormone

4. Effect of vitamin D on markers of insulin resistance and inflammation

Inclusion Criteria:

- Kidney transplant more than 6 months ago

- 19 years or older

- 25-OH vitamin D ≤35 ng/ml

Exclusion Criteria:

- Estimated GFR<30 ml/min/1.73m²

- Previous small bowel or lung transplant

- Pancreas transplant less than 6 months ago

- Cancer or any condition that would change their weight dramatically in the near future
such as malabsorption

- Willing to return for testing every two months

- Women who are pregnant or < 6 weeks postpartum

- Calcium > 10.5 mg/dl

- Phosphate > 4.8 mg/dl

- Drinking more than 2 alcohol drinks a day or 14 drinks per week

- History of parathyroid surgery

- Known granulomatous disease

- Taking any seizure medication that affects vitamin D

- Taking zempler ® and/or Rocaltrol ®

- History of kidney stones in the past 20 years

- Not on a stable dose of bisphosphonate for the past three months

- Planning on a pancreas transplant within the next year

- In any other research study