The Effect of Vitamin D Repletion on Kidney Stone Risk
The Effect of Vitamin D Repletion on Kidney Stone Risk
Examine the effect of nutritional vitamin D repletion on urinary calcium excretion and kidney
 stone burden in calcium kidney stone formers
The investigators plan to conduct a clinic-based interventional study of 50 patients followed
 at Miriam Hospital Kidney Stone Clinic with history of nephrolithiasis, urinary calcium
 excretion between 150 and 400 mg/day, and 25-vitamin D deficiency/insufficiency (defined as
 serum level ≤ 30ng/ml). The intervention is oral ergocalciferol 50,000 IU per week for 12
 weeks (repletion course). After that, the same repletion course will be repeated if serum
 25-vitamin D remains ≤ 30ng/ml or drops to ≤ 30ng/ml anytime during the study. Otherwise, a
 maintenance dose of cholecalciferol 1,000 IU daily or ergocalciferol 50,000 IU monthly will
 be prescribed for the rest of the study. Each participant will serve as his own control. The
 outcome is the change in urinary calcium excretion and stone burden assessed by renal
 ultrasound. The planned study duration is 12 months. The investigators will have greater than
 95% power to detect a 10% increase in 24-hour urinary calcium.
Inclusion Criteria:

 -  History of nephrolithiasis

 -  25(OH)D deficiency (defined as serum level ≤ 30ng/ml) within 3 months of enrollment

 -  24-hour urinary calcium excretion > 150 mg/day and < 400 mg/day (measured less than 2
 months prior to study enrollment)

 Exclusion Criteria:

 -  Known uric acid, cystine, or struvite stone disease

 -  Hypercalcemia (serum calcium >10.4 mg/dl within the past 12 months)

 -  Gross hematuria within the past 6 months

 -  Acute stone event within the past 1 month

 -  Recent stone intervention within the past 1 month

 -  Suspected or known secondary causes of hypercalciuria such as primary
 hyperparathyroidism, sarcoidosis, hyperthyroidism, or malignancy (except non-melanoma
 skin cancer)

 -  Addition or dose change of medicines potentially affecting urinary calcium since
 enrollment 24-hour urine collection (including diuretics, magnesium supplements,
 potassium supplements, potassium citrate, and vitamin D supplementation)

 -  Pregnancy