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Horm Metab Res 1977; 9(4): 321-325
DOI: 10.1055/s-0028-1093521
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© Georg Thieme Verlag KG Stuttgart · New York

The Thyroidal T4/T3 Ratio in Autonomous Adenomas: Correlation with Presurgical Thyroid Status and Iodine Content

D.  Reinwein1 , H. A. Durrer1 , D.  Emrich3 , K.  Littmann2 , E.  Eilers3
  • 1Abteilung für klinische Endokrinologie, Medizinische Klinik der Universität Essen (Gesamthochschule).
  • 2Chirurgische Klinik der Universität Essen (Gesamthochschule).
  • 3Abteilung für Nuklearmedizin, Medizinische Universitätsklinik Göttingen, Germany
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Publication History

Publication Date:
23 December 2008 (online)

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Abstract

In 25 patients with decompensated (n = 16) and compensated (n = 9) autonomous adenoma, the thyroid hormones in serum and the TSH response before operation was compared with intrathyroidal total iodine (TI), PBI, T4 -RIA, T3-RIA and T4/T3 ratio. Autonomous nodular tissue (ANT) and paranodular tissue (PNT) of the operated thyroid gland were hydrolyzed with Pronase under anaerobic conditions. TI, PBI, T4 and T3 were measured in the hydrolysates.

ANT contained significantly higher concentrations of PBI, T4, T3 and a higher T4/T3 ratio than PNT. The most striking difference was found for T4, which amounted to 43.9 ± 10.1 compared with 10.3 ± 4.0 ug/g tissue in PTN. The T4/T3 ratio was 23.1 and thus double as high as in tissue of nontoxic goiter. Between decompensated and compensated autonomous adenomas, only T4 and the T4/T3 ratio were significantly different. No correlations between thyroidal T4/T3 ratio and TI could be found. There was no dependence of serum T4/T3 ratio on the thyroidal T4/T3 ratio whereas, however, a positive correlation between thyroidal T4 and serum T4 could be seen. From these results it is concluded: 1. It is T4 and not T3 that is predominantly produced in autonomous adenoma, and 2. the regulation of the T4/T3 ratio by TI in the tissue is lost.

FT4I for free L-thyroxine index; PBI for protein bound iodine; TI for total iodine; T3 for L-triiodothyronine; T4 for L-thyroxine; TRH for thyrotropin releasing hormone; TSH for thyrotropin.

Key words

Autonomous Adenoma - Intrathyroidal lodothyronines - T4/T3 Ratio - Thyroid Hormones