[Plasma thyroglobulin in treated hypothyroidism in children]

In order to appreciate the value of the dosage of thyroglobulin (Tg) in the reappraisal of the classification of hypothyroidism after the onset of substitutive treatment and the supervision of patients treated with L-thyroxin (LT), plasma Tg and FT4 levels were studied in 42 samples from 21 hypothyroid children (ages ranging from 18 months to 16 years) under LT treatment. These patients were divided into 2 groups according to the results of scanning: group I: a thyroid (n = 8) and group II: ectopic or hypoplastic thyroid gland (n = 13). A control group consisted of 60 apparently healthy children of the same ages. Tg was undetectable in 11 samples of 6 children but significant levels (6.8 to 17 ng/ml) were found in 5 samples of 2 children. In group II, Tg could be measured in 20 of 26 samples, the mean level (+/- SEM) not being different from that in the control group (14.32 +/- 2.25 and 18.12 +/- 1.28 ng/ml, respectively). However, in this group, Tg levels seemed to be lower (9.75 +/- 3.94 ng/ml) in samples from patients with LT excess than in euthyroid or hypothyroid patients whose values of Tg were 15.8 +/- 3.36 ng/ml and 16 +/- 3.91 ng/ml, respectively.