DXA body composition studies are not affected by extracellular water measurements using stable sodium bromide...

Body composition studies using dual energy x-ray absorptiometry (DXA) are being increasingly reported in the literature. When DXA body composition measurements are combined with body water studies, stable bromide is often administered to measure extracellular water. Bromine attenuates x-rays significantly more than soft tissue and so could affect DXA body composition analysis. DXA scans were performed on 26 adults (12 F, 14 M) before and after the intravenous injection of 3 g sodium bromide (NaBr). No significant differences were noted pre- and post-NaBr infusion for whole-body fat mass, fat-free soft tissue mass and bone mineral content. These findings were supported by a simple mathematical analysis of the likely effect of the sodium bromide infusion. This showed that when 3 g NaBr was introduced into the body, the effect on fat mass estimates was expected to be marginally less than the precision of the DXA technique.