Protein-Bound Iodine Level During Childhood and Adolescence

Abstract
Protein-bound iodine (PBI) and butanol-extractable iodine (BEI) levels were collected from published data on 279 male and female euthyroid subjects between 0.1 and 20 yr of age. After allowing for estimated chemical losses and for the estimated ratio of thyroxine iodine to PBI or BEI, the corrected thyroxine iodine level (B4) was studied for age and sex dependence. Empirical formulae were derived to predict the mean B4 for euthyroid subjects of given age and sex. For females, B4 is about 0.2 μg/100 ml higher than for males, a significant difference (p 4 decreases with increasing age to a minimum value at about 15.0 yr for males and 13.7 yr for females, and then rises to approach asymptotically the constant adult level.