LETTER
Prevention of Corticosteroid-Induced Osteoporosis
Timothy C. Birdsall, ND
1 July 1997 | Volume 127 Issue 1 | Page 90
TO THE EDITOR:
Buckley and associates [1] are to be congratulated on their important study evaluating the effectiveness of supplementation with calcium and vitamin D3 in the prevention of corticosteroid-induced bone loss. However, the article contains potentially confusing descriptions of the actual amount of calcium administered to the participants. In at least four separate places, including the abstract and the concluding paragraph, the authors incorrectly state that participants received 1000 mg of calcium carbonate daily. In the Study Design section, they write that "Patients received either calcium carbonate (1000 mg/d) and vitamin D3 (500 IU/d) (two tablets twice a day of Os-Cal 250 + D, SmithKline Beecham Healthcare, Pittsburgh, Pennsylvania) or an identical placebo."
According to the label, Os-Cal 250 + D contains 250 mg of elemental calcium per tablet, derived from calcium carbonate. Because calcium carbonate consists of approximately 40% calcium, Os-Cal 250 + D should contain about 625 mg of calcium carbonate per tablet. A dosage of four tablets daily, as was used in this study, would yield an ingestion of 2500 mg of calcium carbonate, providing 1000 mg of elemental calcium. Consuming 1000 mg of calcium carbonate would have resulted in a calcium dose of only 400 mg. The participants in this study apparently received 1000 mg of elemental calcium, not 1000 mg of calcium carbonate. To avoid confusion and potential misinterpretation of results, it is important that calcium quantities be consistently expressed in elemental terms.
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Author and Article Information
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Sandpoint, ID 83864
1. Buckley LM, Leib ES, Cartularo KS, Vacek PM, Cooper SM. Calcium and vitamin D3 supplementation prevents bone loss in the spine secondary to low-dose corticosteroids in patients with rheumatoid arthritis. A randomized, double-blind, placebo-controlled trial. Ann Intern Med. 1996; 125:961-8.
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