The use of 22Na as a tracer for long-term bone mineral turnover studies.

Sodium-22 has been studied as a tracer for bone mineral metabolism in rats and dogs. When incorporated into bone during growth from birth to adulthood, the bone becomes uniformly tagged with 22Na, which is released through the metabolic turnover of the bone. The 22Na not incorporated in the bone matrix is rapidly excreted within a few days when animals are fed high, but nontoxic levels of NaCl. The 22Na tracer can be used to measure bone mineral loss in animals during space flight and in research on bone disease.