Relationships Between Dual‐Energy X‐Ray Absorptiometry Bone Mineral Content and Bone Mineral Density and Standing and Sitting Bioimpedance Spectroscopy Variables in Healthy Men and Women

Abstract

Bioimpedance spectroscopy (BIS) is an advanced bioimpedance method utilizing data collected over hundreds of frequencies to generate complex Cole models. Standard gel‐backed wet electrodes used on supine patients/subjects has been the accepted method for collecting BIS data which can be used to accurately calculate fluid volumes such as intra‐cellular fluid (ICF), extracellular fluid (ECF), and total body water (TBW) as well as can be used to calculate other tissues and masses. However, the use of metal electrodes used in a standing or sitting position is not well known and offers a more rapid means of performing BIS assessments. If this new method of BIS can predict variables related to bone health, it may have the potential to help track bone loss over time in clinical populations. The purpose of the study was to compare BIS measurements taken when subjects were standing and sitting using fixed metal electrodes and evaluate the relationships of raw and fluid volume data to dual‐energy X‐ray absorptiometry (DXA) data [total bone mineral content (BMC), total bone mineral density (BMD), right forearm BMD (RA_BMD), right femur BMD (RF_BMD), anterior‐posterior spine BMD (APS_BMD)] in healthy men and women. Fifty‐five healthy men and women (m = 22, f = 33, 24 +/− 8 years, 169.5 +/− 10.5 cm, 72.3 +/− 14.9 kg) participated in the study. Whole body right side BIS measurements were taken in both a sitting and standing position with both methods utilizing metal electrodes (SOZO, ImpediMed, Inc.). Whole body DXA scans were performed using a Lunar Prodigy Primo (GE Healthcare). Raw BIS data included R0, Rinf, resistance at 50 kHz (R50), reactance at 50 kHz (Xc50), and phase angle at 50 kHz (Phase50). Calculated fluid volumes from BIS included intra‐cellular fluid (ICF), extra‐cellular fluid (ECF), and total body water (TBW). DXA variables included BMC, BMD, RA_BMD, RF_BMD, and APS_BMD. All raw variables and fluid volumes from BIS were significantly related to all DXA bone variables (p < 0.047) apart from Xc50 for all DXA variables (p > 0.08) other than standing and total BMC (r = −0.269, p = 0.047). Total BMC and ECF resulted in the best relationship for both sitting (r = 0.889) and standing (r = 0.914). However, ICF and TBW were also highly correlated with total BMC (r > 0.860) for both sitting and standing BIS measurements. The next best relationship was between ICF and total BMD (r = 0.815). All standing BIS variables had higher relationships to DXA BMC compared to sitting BIS variables with an average improvement of r = 0.018 (0.002 to 0.056) with the exception of Phase50 (sitting r = 0.629, standing r = 0.617). In conclusion, measurements from BIS in a sitting or standing position with metal electrodes were shown to be highly related to all DXA BMC and BMD measurements with the exception of Xc50. Total body and segmental BMC and BMD may be predicted from multiple BIS variables, yet more research is needed to identify which BIS variables are ideal for each specific bone variable and measurement site. Future research is also needed to identify which BIS variables are optimal for tracking changes in bone over time in both healthy and diseased populations.Support or Funding InformationSupport provided by ImpediMed, Inc. to Eastern Kentucky University. JRM is an employee and stockholder of ImpediMed, Inc.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.