Abstract
In order to determine Tg value in 1) reevaluation of classification of hypothyroidism and 2) follow-up of patients under L.T. plasma Tg and FT4 were determined in 42 blood samples obtained from 21 hypothyroid children under L.T, divided in 2 groups according to the thyroid scans ; group I: athyreosis (n=8) and group II : ectopic or hypoplastic eutopic gland (n=13). Tg concentrations were measured by RIA (lower limit of detection : 3 ng/ml ; sensitivity : 2 ng/ml) after screening for Tg antibodies.
In group I, Tg was undetectable in 11 blood samples obtained from 6 patients, but significant levels of Tg (5.5 to 34 ng/ml) were found in 5 blood samples from 2 patients with negative 123.1 thyroid scan, indicating the presence of some thyroid tissue.
In group II, Tg was detected in 20 of the 26 blood samples, mean (± S D) being statistically not different than in controls (14.32 ± 11.5 and 18.12 ± 9.9 ng/ml respectively). However, Tg levels were significantly lower (9.75 ± 7.8 ng/ml) during excess L.T (FT4 = 43.6 ± 14.5 pmol/l) than during normal (FT4 = 17.4 ± 2.02 pmol/l) or insufficient L.T (FT4 = 8.18 ± 3.19 pmol/l), plasma Tg being respectively 15.18 ± 10.6 and 16 ± 13.6 ng/ml).
In conclusion, 1) Tg is of value in reevaluation of classification of hypothyroidism when significant levels are found in so-called "athyreosis" and 2) Tg is of no value in determining the accurate dosage of L.T in hypothyroid children.
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Colle, M., Latapie, M., Ducassou, D. et al. Plasma Thyreoglobulin (Tg) in hypothyroid children under L. Thyroxine therapy (L.T.). Pediatr Res 18, 1222 (1984). https://doi.org/10.1203/00006450-198411000-00126
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DOI: https://doi.org/10.1203/00006450-198411000-00126