Clinical Approaches to Correcting Vitamin D Inadequacy and Maintaining Adequacy

Inclusion Criteria:

1. Community dwelling men and women age ≥ 65 years.

2. Able and willing to sign informed consent.

3. Serum 25OHD concentration ≥ 10 and less than 60 ng/ml by HPLC.

4. Willing to avoid use of cod-liver oil and non-study vitamin D supplementation;
standard multiple vitamins containing ≤ 400 IU used no more than once daily will be
allowed

Exclusion Criteria:

1. Current hypercalcemia (serum calcium > 10.5 mg/dl) or untreated primary
hyperparathyroidism.

2. History of nephrolithiasis.

3. Screening 25OHD concentration ≥ 60 ng/ml.

4. Baseline 24-hour urine calcium > 250 mg if female, > 300 mg if male.

5. Known risk factors for hypercalcemia, e.g., malignancy, tuberculosis, sarcoidosis,
Paget's disease

6. History of any form of cancer within the past five years with the exception of
adequately treated squamous cell or basal cell skin cancer.

7. Renal failure defined as a calculated creatinine clearance (Cockroft-Gault method) ≤
25 ml/minute

8. Severe end-organ disease, e.g., cardiovascular, hepatic, hematologic, pulmonary,
etc., which may limit ability to complete the study

9. Known malabsorption syndromes, e.g., celiac disease, radiation enteritis, active
inflammatory bowel disease, etc.

10. Use of medications known to alter bone turnover including bisphosphonates, estrogen,
selective estrogen receptor modulators, PTH, testosterone or calcitonin

11. Vitamin D intake greater than 5,000 IU daily

12. Treatment with any active metabolites of vitamin D within six months of screening

13. Treatment with any drug which may interfere with vitamin D metabolism, e.g.,
phenobarbital, phenytoin.