Clinical Trial: The Effect of Vitamin D Supplementation on Calcium Excretion in Thalassemia: a Dose Response Study

Study Status: Suspended
Recruit Status: Unknown status
Study Type: Interventional

Official Title: The Effect of Vitamin D Supplementation on Calcium Excretion in Thalassemia: a Dose Response Study

Brief Summary: The purpose of this pilot study is to determine the effect of various doses of vitamin D supplementation on vitamin D stores and calcium excretion in the urine in subjects with Thalassemia Major (TM). Subjects with TM are routinely placed on vitamin D supplements because they frequently have osteoporosis (a condition in which bone tissue thins and loses density and strength) and low vitamin D stores. The amount of vitamin D supplementation that is required to raise vitamin D stores in optimal levels is not known in TM, and will be determined in this study. Finally, a recent study in TM has linked blood vitamin D levels to urine calcium excretion, which is a risk factor for kidney stones. Therefore, we want to determine changes in calcium excretion with various vitamin D doses and with increasing vitamin D stores. We plan to test 3 doses of vitamin D for 3 months in children and adults with TM. Changes in vitamin D blood levels and urinary calcium will be determined. The results of this pilot study will be used in future studies that will examine the effect of various doses of vitamin D supplementation in the treatment of osteoporosis in TM.

Detailed Summary:

Specific Aim: To determine the effect of various doses of vitamin D supplementation on serum concentration of 25 hydroxy vitamin D (25OHD) and urinary calcium excretion in adults and children with TM.

Hypothesis: Vitamin D supplementation at doses that result in serum 25OHD levels >30 ng/ml result in high rates of hypercalciuria (i.e. increased urinary calcium excretion) in children and adults with TM.

The pilot study will be performed at Weill Cornell Medical College, Payson 695.

  • Children and adults with TM, will be divided into 4 groups: "standard" vitamin D dose (equivalent to 400 IU/day), "intermediate" vitamin D dose (equivalent to 1000 IU/day), "high" vitamin D dose (equivalent to 2,000 IU/day) and a "placebo" group that will receive an inactive ingredient. 10 subjects will be assigned to each group. The duration of the study will be 3 months.
  • While some studies found no difference between vitamin D2 and D3, others suggest that vitamin D3 may be more advantageous in restoring 25 OHD concentrations. For these reasons, vitamin D3 will be used in this protocol.
  • Study schedule with study interventions and frequencies is set out below (see table). All 4 groups will adhere to the same schedule. After obtaining consent, subjects will have a "Baseline Visit", which will include: 1) a complete physical examination; 2) laboratory evaluation that includes measurement of 25OHD, which is the major circulating form of vitamin D and reflects the body's vitamin D stores. Additional blood and urine samples will be obtained for measurement of urinary calcium excretion and serum Calcium and parathyroid hormone (PTH); and 3) Dietary ca
    Sponsor: Weill Medical College of Cornell University

    Current Primary Outcome: Vitamin D Dose Response Curve [ Time Frame: 3 Months ]

    To perform a dose response curve for vitamin D supplementation study and determine the relationship between vitamin D doses and serum 25OHD concentrations and urinary calcium excretion in children and adults with TM.


    Original Primary Outcome: Same as current

    Current Secondary Outcome: Vitamin D Dose Response Curve [ Time Frame: 3 Months ]

    To determine changes in serum calcium and PTH concentrations with various vitamin D doses


    Original Secondary Outcome: Same as current

    Information By: Weill Medical College of Cornell University

    Dates:
    Date Received: March 24, 2011
    Date Started: June 2011
    Date Completion: December 2014
    Last Updated: April 18, 2011
    Last Verified: April 2011