Application of in vivo activation analysis to the compartmental study of sodium in the hand

Sodium kinetics were studied in the hands of 14 subjects by local in vivo neutron activation analysis. Hands were irradiated with 252 Cf sources giving absorbed doses of 8 cGy. The variation in 24Na radioactivity was plotted against time, and each curve fitted to a function that was the sum of two exponentials. Two pools were identified, one corresponding to fast turnover, with a half-life of about one hour, the other to a slower turnover process with a half-life averaging 79 h if the calcium concentration of the hand bones is normal, and 35 h if it is subnormal. The mean ratio of calcium to slowly exchangeable sodium is estimated to be 47.7, and the ratio of quickly exchangeable sodium to slowly exchangeable sodium to be 0.65. These various parameters should be of interest in bone pathology.