Zinc & Bone Health in Thalassemia: The Think Zinc Study (ThinkZn)

National Heart, Lung, and Blood Institute (NHLBI), Children's Hospital of Philadelphia, University of California, San Francisco

The purpose of this study is to test whether zinc can improve bone health in young patients with thalassemia.

The primary aim of this study is to determine if zinc supplementation improves bone health in young patients with thalassemia. Osteoporosis is a significant co-morbidity in patients with thalassemia which leads to decreased quality of life. The most effective way to prevent osteoporosis is to build strong, dense bones in the early years. A combination of disease, endocrine and nutritional factors likely contribute to the etiology of osteoporosis in this population. However, even well transfused patients with normal gonadal function who are supplemented with calcium have low bone mass. It is hypothesized that patients with thalassemia have low bone mass, in part, due to zinc deficiency. Sub-optimal zinc status has been identified in patients with thalassemia and zinc supplementation has been shown to improve linear growth. To test the primary hypothesis, an 18 month randomized placebo-controlled trial of zinc supplementation (25 mg Zn/day) vs. placebo will be conducted in 60 young patients (6-30 yrs) with thalassemia and low bone mass (spine BMD Z-score <-1.0). Bone health, as estimated from measurements of bone mass (by DXA and pQCT) and markers of bone formation and resorption will be the primary outcome variables. This will be the first study to examine the effects of zinc. supplementation on bone health in patients with thalassemia. If zinc supplementation is found to have a clinically important effect, this simple, safe, non-invasive therapy could quickly become a part of the standard care of these young patients and improve overall health in children and adult patients with thalassemia

Placebo capsule, identical to the zn capsule in size, shape and color, taken once daily for 18 months

Absolute change in serum osteocalcin between 0 and 18 months, intention to treat analysis between the zinc and placebo groups

Inclusion Criteria: 6 to 30 years of age thalassemia bone mineral density Z-score < -1.0 (by DXA) Exclusion Criteria: Bone marrow transplant recipient Currently prescribed treatment for low bone mass other than calcium or vitamin D (e.g. calcitonin, bisphosphonates) Currently prescribed zinc supplementation who are unable or unwilling to stop during this trial Currently participating in another trial with a medication known to affect bone mineral density. Chronic use of systemic corticosteroids Untreated hypogonadism or growth hormone deficiency Baseline serum copper < 70 µg/dL Baseline vitamin D-25OH < 11 ng/mL Pregnant or lactating at study entry

Fung EB, Kwiatkowski JL, Huang JN, Gildengorin G, King JC, Vichinsky EP. Zinc supplementation improves bone density in patients with thalassemia: a double-blind, randomized, placebo-controlled trial. Am J Clin Nutr. 2013 Oct;98(4):960-71. doi: 10.3945/ajcn.112.049221. Epub 2013 Aug 14.