Tests for hypothyroidism in school children.

Abstract

Venous blood samples were obtained from 1,759 children, 6 to 14 years of age, in 12 schools in Los Angeles with a total enrollment of 2,502. Serum protein-bound iodine (PBI) and cholesterol were measured and 131I T3 resin uptake and T4 iodine were determined by column tests. For 139 children, column values for T4 iodine were compared with manual PBI results in the same sera; the means were, respectively, 4.7 and 5.6 μ g. per 100 ml. Semiautomated Robot Chemist PBI values (range 4.0 to 8.1) were compared with manual PBI values (range 3.2 to 13.2). The percentages of 131I T3 resin uptake had a negative correlation with the PBI values, coefficient –0.31096. No diagnostic value of this test was evident. In serum PBI determinations done by the manual technic for 570 Caucasian school children, 4.5% of the values were below 4 μ g. per 100 ml. These children were studied for evidence of need for thyroxine medication; 2.6% are being treated. Examples of high serum PBI levels maintained for three years on thyroxine medication are shown. It is suggested that biochemical values affected by hypothyroxinemia should be used to establish the diagnosis of hypothyroidism, of thyroid hormone in the serum.