The development of a whole-body potassium counter for the measurement of body cell mass in adult humans

Saba Naqvi ； Kishor G Bhat ； Thomas Preston ； Sarita Devi ； Jayakumar Joseph ； Harshpal S Sachdev ； Anura V Kurpad ； Rebecca Kuriyan

《Asia Pacific Journal of Clinical Nutrition》 27卷6期 (2018/11) Pp. 1190-1197

https://doi.org/10.6133/apjcn.201811_27(6).0004

摘要

Background and Objectives: Total body potassium (TBK), has a natural radioactive isotope, which can be measured to derive body cell mass (BCM), making it useful in clinical conditions, early growth and pregnancy. The objective was to build a whole-body potassium counter (WBKC), to accurately measure TBK in the body. Methods and Study Design: A WBKC was designed and constructed using a shadow shield. A cellular four compartment (4C) model of fat free mass (FFM), using estimates of TBK along with total body water (TBW), was compared with a molecular 4C model of the body in twenty healthy adults (10 men and 10 women). The molecular 4C model used measurements of TBW, bone mineral content (BMC), and body volume from deuterium dilution (DD), dual energy x-ray absorptiometry (DXA) and air displacement plethysmography (ADP) respectively. Results: The accuracy and precision of the WBKC were 2.8% and 1.9% with TBK phantoms. The mean estimate of FFM by the molecular 4C model was 40.4±6.8 kg, while it was 41.2±7.3 kg using the cellular 4C model. Conclusions: A WBKC constructed from base principles, was relatively low cost, efficient, safe and noninvasive, but requires some design considerations. Its measurement of FFM compared well with the molecular 4C model. Once constructed, it offers a relatively costless, accurate and repeatable method to measure body composition in conditions with uncertain hydration status, at all life stages.

關鍵字

whole-body potassium count ； body composition ； body cell mass ； potassium ； fat free mass