Total Body Potassium Counting

This extremely sensitive device measures the gamma rays emitted from an isotope of potassium known as ⁴⁰K, which exists naturally in the human body at a known natural abundance (0.012%).  This knowledge, plus the fact that potassium is only found inside body cells and is not present in stored triglycerides, makes ⁴⁰K data an accurate index of the body's total cell mass (the active growing tissues in the body), which in turn can be used to estimate fat-free mass.*

*Although the terms lean body mass (LBM) and fat free mass (FFM) are often used interchangeably, it is more accurate to think of body weight (mass) as the sum of LBM (muscles, organs and other non-fat tissues such as bone) plus adipose (fat) tissue, or alternatively, as the sum of extractable fat (i.e., the pure fat component of adipose and other tissues) plus fat-free mass (FFM), with FFM including the water, protein and other non-fat components of adipose and other fat-containing tissues.