Avoid calcium supplements at time of DXA
J Clin Densitom, 2006 Summer;9(2):159-63 Epub 2006 Apr 18. Krueger D and others, Calcium supplement ingestion may alter lumbar spine bone mineral density measurement. PMID: 16785075. The authors note that it is often suggested that patients abstain from ingesting calcium supplements before dual-energy X-ray absorptiometry (DXA) to avoid interference with the test results. (Editor's comment: I don't recall ever being told to avoid supplements, although I don't believe I've taken them just before the test either). The purpose of this study was to see if recent calcium supplement ingestion would affect lumbar spine bone density testing. The authors did a three-phase test and noted that: “In conclusion, calcium tablet intake may affect measured L1-L4 BMD within 30 minutes of ingestion. As such, it is appropriate to request patients abstain from calcium tablet ingestion prior to a spine DXA examination.” Editor's comment: Obviously if calcium supplements affect DXA results, it would be to make bone density appear higher than it is—exactly what you wouldn't want to have happen. So to be on the safe side, avoid calcium supplements on the day of a DXA exam.