COMPARISON OF BODY-COMPOSITION MEASURED BY TOTAL-BODY POTASSIUM AND INFRARED INTERACTANCE

Objective: The purpose of this study was to find how closely a near in frared instrument (IRI), Futrex 5000, would compare to whole body coun ting (WBC) of potassium-40 (K-40) in assessing body composition. Desig n: We measured lean body mass (LBM) and percent total body fat (PCF) i n 177 males and 27 females by total body potassium (TBK) and by infrar ed interactamce (IRI). TBK was assessed by 2 pi whole body counter (WB C) and IRI by Futrex (F) instrument. These subjects were measured for TBK and for IRI within 1 week of each other. Result: A large mean diff erence (p less than or equal to 0.001) was found between the results u sing the two instruments: IRI data for LBM were higher and PCF lower c ompared to TBK. Conclusion: As shown by repeated TBK measurements over a 22-year period in these same volunteers, this technique is reliable . The IRI assessments did not come to a close fit with TBK.