3,5,3’-Triiodothyroacetic Acid (TRIAC) Effects on Pituitary Thyroid Regulation and on Peripheral Tissue Parameters

 

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The effects of TRIAC on peripheral thyroid hormones, TSH incretion and peripheral tissue parameters were investigated in 13 mildly obese patients (group I) and 10 volunteers of normal body weight (group II). TRIAC was administered 3x1 mg daily over a period of 8 days to both groups. In group I (on a 400 kcal low caloric diet) bTSH and fT₄ decreased significantly whereas TT₄ decreased only insignificantly. TT₃ and fT₃ rose significantly due to the cross-reactivity of the employed antibody. The peripheral tissue parameters cholesterol, ankle jerk and systolic time interval did not reveal any changes suggesting an increase in metabolic rate. The increase in heart frequency was not significant either. The significant rise in sex-hormone binding globulin was most probably associated with the weight reduction of 3.1 ± 1.2 kg per week. In group II (on normal diet) bTSH and fT₄ decreased significantly whereas TT₄ decreased only insignificantly. As in group I, TT₃ and fT₃ rose significantly. Also in group II TRIAC did not cause alterations in the peripheral tissue parameters. In contrast to the obese group the volunteers in group II showed no significant rise in sex-hormone binding globulin and no reduction of body weight. Side effects such as nervousness, tremor or palpitations were not observed. Thus, TRIAC does not induce an increase in peripheral metabolic rate, not even under a TSH-suppressive dose as high as 3 x 1 mg per day.

Zusammenfassung

An 13 adipösen Patienten (Gruppe I) und 10 normalgewichtigen Probanden (Gruppe II) wurde der Einfluß von TRIAC auf die Schilddrüsenhormone, die TSH-Inkretion und die peripheren Gewebsparameter untersucht. TRIAC wurde in einer Dosierung von 3×1 mg pro die über 8 Tage verabreicht. In Gruppe I (400 kcal Reduktions-Diät) sanken bTSH und fT₄ signifikant während TT₄ nur insignifikant abfiel. Dagegen stiegen TT₃ und fT₃ aufgrund der Kreuzreaktivität des verwendeten Antikörpers signifikant an. Die peripheren Gewebsparameter Cholesterin, Achilles-Sehnen-Reflex und systolische Zeitintervalle zeigten keine Veränderungen im Sinne einer Stoffwechselsteigerung. Die Zunahme der Herzfrequenz war ebenfalls nicht signifikant. Der signifikante Anstieg des sexhormonbindenden Globulins ist in Zusammenhang mit der Gewichtsreduktion von 3.1 ± 1.2 kg pro Woche zu beurteilen. In Gruppe II (ohne Reduktions-Diät) sanken bTSH und fT₄ signifikant, während TT₄ nur insignifikant abfiel. Wie in Gruppe I stiegen TT₃ und fT₃ signifikant an. Auch in Gruppe II verursachte TRIAC keine Veränderungen der peripheren Gewebsparameter. Im Gegensatz zur adipösen Gruppe kam es jedoch bei den normalgewichtigen Probanden der Gruppe II zu keinem signifikantem Anstieg des sexhormonbindenden (SHB) Globulins und zu keiner Gewichtsreduktion. Nebenwirkungen wie Nervosität, Tremor oder Palpitationen konnten nicht beobachtet werden. TRIAC führt somit auch unter einer hohen TSH-suppressiven Dosis von 3 × 1 mg pro Tag zu keiner peripheren Stoffwechselsteigerung.

• REFERENCES

• 1 Beck-Peccoz P, Piscitelli G, Cattaneo M G, Faglia G. Successful treatment of hyperthyroidism due to non-neoplastic pituitary TSH hypersecretion with 3,5,3’-triidothyroacetic acid (TRIAC). J Endocrinol Invest 1983; 06: 217-23.
  CrossrefGoogle Scholar
• 2 Beck-Peccoz P, Sartorio A, De Medici C. et al. Dissociated thyromimetic effects of 3,5,3’-triiodothyroacetic acid (TRIAC) at the pituitary and peripheral tissue levels. J Endocrinol Invest 1988; 11: 113-8.
  CrossrefGoogle Scholar
• 3 Burger A, Valloton M B. The metabolism of tetraiodothyroacetic acid and its conversion to triiodothyroacetic acid in man. In: Harland W A, Orr J S. (eds.). Proc Internat Conf Thyroid Hormone Metabolism. London: Academic Press; 1975: 223.
  Google Scholar
• 4 Burger A G, Engler D, Sakoloff C, Stacheli V. The effects of tetraiodothyroacetic and triiodothyroacetic acid on thyroid function in euthyroid and hyperthyroid subjects. Acta Endocrinol 1979; 92: 455-67.
  Google Scholar
• 5 Gavin L A, Livermore B M, Cavalieri R R, Hamond M E, Castle J N. Serum concentration, metabolitic clearance, and production rates of 3,5,3’-triiodothyroacetic acid in normal and athyreotic man. J Clin Endocrinol Metab 1980; 51: 529-34.
  CrossrefGoogle Scholar
• 6 Glass A R, Swerdloff R S, Bray G A, Dahms W T, Atkinson R L. Low serum testosterone and sex-hormone-binding globulin in massively obese men. J Clin Endocrinol Metab 1977; 45: 1211-9.
  CrossrefGoogle Scholar
• 7 Hennemann G, Docter R, Krenning E P. Causes and effects of the low T₃ syndrome during caloric deprivation and non-thyroidal illness: an overview. In: Eber O, Leb G, Denk H, Langsteger W. (Hrsg.). 2nd Thyroid Symposium Peripheral Thyroid Hormone Metabolism. Acta Med Austriaca. 1988. Suppl 1: 41-4.
  Google Scholar
• 8 Koerner D, Schwartz H L, Surks M I, Oppenheimer J H, Jorgensen E C. Binding of selected iodothyronine analogues to receptor sites of isolated rat hepatic nuclei: high correlation between structural requirements for nuclear binding and biological activity. J Biol Chem 1975; 250: 6417-23.
  Google Scholar
• 9 Lind P, Eber O. Behandlung der inappro- priaten TSH-Inkretion mit TRIAC. Acta Med Austria 1986; 13: 13-7.
  Google Scholar
• 10 Medeiros-Neto G, Kallas W G, Knobel M, Cavaliere H, Mattar E. Triac (3,5,3’- triiodothyroacetic acid) partially inhibits the thyrotropin response to synthetic thyrotropin-releasing hormone in normal and thy- roidectomized hypothyroid patients. J Clin Endocrinol Metab 1980; 50: 223-25.
  CrossrefGoogle Scholar
• 11 Mueller-Gaertner H W, Schneider C. 3,5,3’- triiodothyroacetic acid minimizes the pituitary thyrotropin secretion in patients on levo-thyroxine therapy after ablative therapy for differentiated thyroid carcinoma. Clin Endocrinol 1988; 28: 345-51.
  CrossrefGoogle Scholar
• 12 Oppenheimer J H, Schwartz H L. Stereo- specific transport of triiodothyronine from plasma to cytosol and from cytosol to nucleus in rat liver, kidney, brain and heart. J Clin Invest 1985; 75: 147-52.
  CrossrefGoogle Scholar
• 13 Roche J, Michel R, Jouan P, Wolf W. The recovery of 3,5,3’-triiodothyroacetic acid and 3,3’-diiodothyronine from rat kidney after injection of 3,5,3’-triiodothyronine. Endocrinology 1956; 59: 425-8.
  CrossrefGoogle Scholar
• 14 Wawschinek O, Eber O, Petek W, Wakonig P, Gürakcr A. Bestimmung der Harnjodidausscheidung mittels einer modifizierten Cer-Arsenitmethode. Berichte der ÖGKC 1985; 08: 13-5.
  Google Scholar