Determination of potassium in the skeletal muscles by whole-body counting.

Changes in muscular function are related to nutritional status, disease and physical activity. To study these relationships, it is desirable to be able to determine the whole body potassium content, which is characteristic to the muscular tissue. This can be achieved by measurements in a whole-body counter, identifying contributions from the upper and lower parts of the body. In a whole-body counter with large plastic scintillators, a special measuring methodology is required. Such a method of measuring (40)K in the leg muscles, extracting the part of the detector signal originating from the lower part of the body, has been developed and tested by independent phantom measurements. The results suggest that it is suited to perform regional measurements of body potassium but validation and implementation into clinical research are still necessary.