Calibration of a total body potassium monitor with an anthropomorphic phantom.
An anthropomorphic phantom was used to calibrate a supine geometry sodium iodide total body potassium monitor. Correction factors accommodating variability in subject size were empirically determined. Measurements on 12 males of weight 45-96 kg, height 161-184 cm and 18 females of weight 48-89 kg, height 153-175 cm, showed that the 40K calibration factor (F, counts s-1 (g of potassium)-1) was significantly correlated (r = 0.88, p < 0.0001) to subject (weight/height)0.5, indicating comparable accuracy to 42K-based calibration procedures. Fat-free mass determined from the potassium measurements of 16 subjects correlated significantly with fat-free mass estimated from skinfold thickness (r = 0.98, p < 0.0001), dual-energy x-ray absorptiometry (r = 0.99, p < 0.0001) and bioimpedance analysis (r = 0.98, p < 0.0001). These data, together with the precision (coefficient of variation, CV = 1.5%) and accuracy (CV = 4.5%) of the system, indicate that this calibration procedure represents a relatively low-cost, non-invasive alternative to 42K-based methods of calibrating total body potassium monitors.
Hansen
R D
RD
Department of Life Sciences MO2, University of Sydney, NSW, Australia.
Allen
B J
BJ
D015502:Absorptiometry, Photon / Q000379:methods; D000328:Adult; D000368:Aged; D000886:Anthropometry / Q000379:methods*; D001824:Body Constitution; D001827:Body Height; D001835:Body Weight; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019047:Phantoms, Imaging; D011188:Potassium / Q000032:analysis*; D011197:Potassium Radioisotopes; D012044:Regression Analysis; D012885:Skinfold Thickness; D012974:Sodium Iodide
D011197:Potassium Radioisotopes; D012974:Sodium Iodide; D011188:Potassium