title: Potential errors in body composition as estimated by whole body scintillation counting.
abstract: Vigorous exercise has been reported to increase the apparent potassium content of athletes measured by whole body gamma ray scintillation counting of 40K. The possibility that this phenomenon is an artifact was evaluated in three cyclists and one nonathlete after exercise on the road (cyclists) or in a room with a source of radon and radon progeny (nonathlete). The apparent 40K content of the thighs of the athletes and whole body of the nonathlete increased after exercise. Counts were also increased in both windows detecting 214Bi, a progeny of radon. 40K and 214Bi counts were highly correlated (r = 0.87, p less than 0.001). The apparent increase in 40K was accounted for by an increase in counts associated with the 1.764 MeV gamma ray emissions from 214Bi. Thus a failure to correct for radon progeny would cause a significant error in the estimate of lean body mass by 40K counting.
mesh_terms: D000293:Adolescent; D000328:Adult; D001729:Bismuth / Q000032:analysis; D001823:Body Composition; D005189:False Positive Reactions; D006801:Humans; D008297:Male; D005082:Physical Exertion; D011188:Potassium / Q000032:analysis*; D011197:Potassium Radioisotopes / Q000032:analysis*; D011868:Radioisotopes / Q000032:analysis; D012588:Scintillation Counting / Q000592:standards*
chemical_list: D011197:Potassium Radioisotopes; D011868:Radioisotopes; D011188:Potassium; D001729:Bismuth