Vitamin D for Sickle-cell Respiratory Complications

This study will be a Phase 2 double-blind randomized clinical trial in 80 patients with sickle cell disease, ages 3 to 20 years-old, comparing a 2-year monthly oral dose of vitamin D3, 100,000 IU (equivalent to 3,300 IU/day) to a standard monthly dose, 12,000 IU (400 IU/day) in reducing the rate of respiratory events (defined as respiratory infections, acute asthma exacerbation, and the acute chest syndrome) in children and adolescents with sickle cell disease in comparison with the rates of respiratory events over a baseline period of one year.

Eligible participants (130 patients) will initially be screened to determine their blood vitamin D levels (serum 25-hydroxyvitamin D). Those with 25-hydroxyvitamin D levels between 5 and 60 ng/mL will be eligible for randomization. At study entry, blood and urine samples will be collected for routine and special blood tests including tests on immune function, inflammation, and bone function. Children above 5 years old will also have lung function and muscle strength tests. Participants will be followed once a month to administer the study medication (oral vitamin D3) and to monitor any side effects from the study medication by history, examination and blood and urine tests. After 12 and 24 months of therapy, the same study procedures at study entry will be repeated.

This study could help establish oral vitamin D3 as a simple, low cost treatment to reduce respiratory complications in children and adolescents with sickle cell disease.

Inclusion criteria

• Diagnosis of sickle cell disease (HbSS, HbSC, HbS Beta-thalassemia)
• Age 3 to 20 years old

Exclusion criteria

• Patient (or parent or guardian) unwilling or unable to provide written informed consent (and assent, if applicable)
• Patient unable or unwilling to comply with requirements of the clinical trial
• Participation in other therapeutic clinical trial
• Current diagnosis of rickets
• History of hypercalcemia or diagnosis of any medical condition associated with hypercalcemia, including primary hyperparathyroidism, malignancy, sarcoidosis, tuberculosis, granulomatous disease, familial hypocalciuric hypercalcemia
• Current use of corticosteroids, excluding inhaled steroids
• Current use of anticonvulsants (phenytoin, phenobarbital, carbamazepine)
• Therapy with thiazide diuretics or lithium carbonate
• Known liver or renal disease
• Patients taking medications for pulmonary complications of sickle cell disease not on a stable dose of medications, as defined by a change in medications or doses within the three months prior to study entry
• Patients on chronic red blood cell transfusion therapy
• Absence of baseline record of respiratory events (respiratory infections, asthma exacerbations, episodes of acute chest syndrome) for the preceding year
• Pregnancy