35 TSH concentrations were normal. For this reason, TBG-binding capacities were determined in a numberof subjects with abnormal! T, values. TBG analyses were done on sera from 56 subjects (25 Rongelap and 31 Utirik) selected as representative of three groups: people with low, normal, or high plasnra T, concentrations. Two methods were used: TBG was measured byradioimmunoassay (M.C, Gershengorn and J. Robbins, unpublished observations, 1974) and TBG-bind- ing capacity by reverse-flow paper electrophoresis. The results were comparable since the meanratio of TBG-binding capacity (ug T4/dl) to TBG (mg/dl) was 13.9. On the basis of one mole Ty Table 31 Total and Free Thyroxine, Thvroxine-Binding Globulin, and Thyrotropin Levels in Marshallese Subject No. TBG,ug/dl Ts, g/dl DFT, x 104 Free Ty, ng/d] TSH, #Uml 3.1 4.4 4.4 4.4 4.9 4.0 4.1 3.37 3.53 3.24 3.21 3.20 3.76 4.23 1.72 1.55 1.43 1.41 1.57 1.50 1.73 3.1 2.3 <1.0 <5.0 <2.5 3.2 3.8 4.6 3.12 2.94 2.80 0.998 1.12 1.29 4.2 3.6 <2.5 3.33 1.44 Subjects with TBG-bind capacity < 14 ug T4/dl 827 917 981 2115 2126 2144 2174 7.6 (1.06) * 7.0 (1.20) 8.0 (0.69) 77 9.1 70 7.1 2193 11.1 (1.03) 2220 2248 2185 13.7 11.9 (0.94) Mean S.D. 9.02 72.39 48 4.34 0.543 Subjects with TBG-binding capacity 14 to 26 ug T4/dl 850 14.0 (1.04) 2135 2137 (5.5 (1.06) 17 2.15 1.66 4.2 6.1 1.45 0.885 1.53 +£2.58 1.87 +0.503 0.597 9.0 35.7 56.1 (4.56) 5.9 12.9 2256 47.6 (3.92) 32.8 S.D. 1.14 2.60 37.0 (1.32) Mean 2.72 5.9 2229 891 911i 2217 1.84 1.79 2.67 16.65 Subjects with TBG-binding capacity >26 ug T,/dl 2138 <2.5 2.05 1.46 0.912 1.29 1.16 2.57 - 21.9 (1.2B) S.D. 0.92 2.77 2.92 3.04 2.68 2.42 2.94 14.1 Mean 2.6 7.4 5.0 3.0 4.8 48 88 3.0 2.94 2.90 1.42 17.7 14.4 14.3 15.6 16.2 (1.54) 17.3 2168 2230 3.08 2.01 1.81 2.5 2.1 49 2.4 10.8 2.1 0.991 1.80 4.4 51.8 18.2 43.5 11.05 1.42 1.43 +0.468 +0.358 *TBG bv RIA. mg/ml. 2.8 <2.5 3.6 <5.0 6.0 2.0 0.903 1.54 0.872 1.88 4.63 2.1 2.6 1.53 1.22 13.6 7.0 9.62 <1.0 *+0.230 6.1 9.2 20.1 2136 0.40 1.35 15.5 19.9 (1.37) 2212 2206 2182 2218 2221 2232 2257 4.6 3.23 1.19 1.32 2.7