55 TSH concentrations were normal. For this reason, methods were used: TBG was measured byradio- Jects (25 Rongelap and 31 Utirik) selected as rep- The results were comparable since the meanratio of TBG-binding capacity (ug T4/dl) to TBG TBG-binding capacities were determined in a numberof subjects with abnormal T, values. TBG analyses were done on sera from 56 subresentative of three groups: people with low, nor- mal, or high plasnva T4 concentrations. Two immunoassay (M.C. Gershengorn and J. Robbins, unpublished observations, 1974) and TBG-binding capacity by reverse-flow paper electrophoresis. (mg/dl) was 13.9. On the basis of one mole T, Table 31 Total and Free Thyroxine, Thyroxine-Binding Globulin, and Thyrotropin Levels in Marshallese Subject No. TBG,pe/dl Ts, pg/dl Subjects with TBG-bind capacity <14 ug T4/dl 827 917 981 2015 2126 2144 2174 2193 2220 2248 2185 7.6 (1.06) * 7.0 (1.20) 8.0 (0.69) 7.7 9.1 7.0 7.1 11.1(1.03) 13.7 11.9 (0.94) - Mean S.D. 9.02 *+2.39 5.1 4.4 4.4 4.4 4.9 4.0 4.1 48 3.2 3.8 4.6 4.34 *0.543 Subjects with TBG-binding capacity 14 to 26 ug T4/ 850 14.0 (1.04) 4.6 2135 15.5 6.1 2137 19.9 (1.37) 9.2 2212 20.1 3.0 2206 17.7 7.4 2182 14.4 5.0 2218 14.3 3.0 2221 15.6 2232 2257 2168 2136 2230 16.2 (1.54) 17.3 14.1 15.5 (1.06) - 21.9 (1.28) Mean 5.D. 4.8 4.8 8.8 4.2 7.7 6.1 S.D. 3.37 3.53 3.24 3.21 3.20 3.76 4.23 3.23 3.12 2.94 2.80 3.33 Free T4, ng/dl 1.72 1.55 1.43 1.41 1.57 1.50 1.73 1.55 0.998 1.12 1.29 1.44 3.08 2.94 2.90 1.84 2.77 2.92 3.04 1.42 1.79 2.67 0.92 2.05 1.46 0.912 2.6 2.1 2.6 <2.5 28 <2.5 3.6 2.42 2.94 2.72 2.15 1.45 1.16 2.57 1.14 1.66 0.885 6.0 2.0 <2.5 2.1 4.9 2.68 1.29 3.9 2.60 1.33 +1.87 +0.503 +0.597 2.01 1.53 1.22 0.872 1.88 0.991 1.81 0.903 1.54 1.19 1.32 1.80 1.42 1.43 +9.62 *TBG bv RIA, mg/ml. 11.05 +4.63 3.1 2.3 <1.0 <35.0 <2.5 <1.0 4.2 3.6 <2.5 +0.230 16.65 43.5 TSH, pU mi 0.40 *#2.58 Subjects with TBG-binding capacity > 26 pg T,/dl 2138 37.0 (1.52) 9.0 2229 35.7 5.9 891 56.1 (4.56) 12.9 911 47.6 (3.92) 13.6 2217 32.8 7.0 2256 51.8 18.2 Mean DFT, x 104 +0.468 +0.358 <35.0 2.4 10.8 2.1 2.7 4.4