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Replacement therapy with levothyroxine plus triiodothyronine (bioavailable molar ratio 14 : 1) is not superior to thyroxine alone to improve well-being and cognitive performance in hypothyroidism.
Clin Endocrinol (Oxf) 2004; 60(6):750-7CE

Abstract

OBJECTIVES

There is evidence from recent controlled clinical studies that replacement therapy of hypothyroidism with T4 in combination with a small amount of T3 may improve the well-being of the patients. As the issue is still the subject of controversial discussion, our study was assigned to confirm the superiority of a physiological combination of thyroid hormones (absorbed molar ratio 14 : 1) over T4 alone with regard to mood states and cognitive functioning.

DESIGN AND PATIENTS

After a run-in period with the T4 study medication for 4 weeks, a controlled, randomized, double-blind, two-period (each 12 weeks), cross-over study without washout between the treatment periods was performed in 23 hypothyroid patients (three males, 20 females, age 23-69 years, 21 subjects after surgery/radioiodine, two with autoimmune thyroiditis) to compare the effects of the previous individual T4 dose (100-175 micro g) with a treatment in which 5% of the respective T4 dose was substituted by T3.

MEASUREMENTS

Standard hormonal characteristics and standardized psychological tests to quantify mood and cognitive performance were measured after the run-in period and at the end of each treatment period. In 12 subjects, the concentration-time profiles of fT3 and fT4 were compared after the last administration of the respective study medication. TSH, fT3 and fT4 were measured with immunological assays.

CLINICAL RESULTS

Replacement therapy with T4 and T4/T3 was not different in all steady-state hormonal, metabolic and cardiovascular characteristics except for TSH, which was more suppressed after T4/T3. The efficacy of replacement therapy with the T4/T3 combination was not different from the T4 monotherapy with regard to all psychological test scores describing mood and cognitive functioning of the patients. Mood was even significantly impaired by the T4/T3 combination in eight subjects, with TSH < 0.02 mU/l, compared to patients with normal TSH (Beck Depression Inventory: 8.25 +/- 5.01 vs. 4.07 +/- 5.60, P = 0.026). PHARMACOKINETIC RESULTS: The area under the concentration-time curve (AUC(0-8h)) of fT3 was significantly higher after T4/T3 compared to the T4 monotherapy (42.8 +/- 9.03 pmol x h/l vs. 36.3 +/- 8.50 pmol x h/l, P < 0.05) and was significantly correlated to serum TSH (r(s) = -0.609, P < 0.05). After T4/T3, patients with a history of Graves' disease or autoimmune thyroiditis had significantly higher serum trough levels of fT3 whereas the fT4 concentrations were significantly lower in patients with a nonautoimmune background.

CONCLUSION

Replacement therapy of hypothyroidism with T4 plus T3 does not improve mood and cognitive performance compared to the standard T4 monotherapy. There is even a higher risk of signs of subclinical hyperthyroidism associated with impaired well-being of the patients, which is clearly caused by significant fluctuations in the steady-state fT3 serum concentrations.

Authors+Show Affiliations

Department of Clinical Pharmacology of the Peter Holtz Research Centre of Pharmacology and Experimental Therapeutics, Ernst Moritz Arndt University, Greifswald, Germany.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Clinical Trial
Comparative Study
Journal Article
Randomized Controlled Trial

Language

eng

PubMed ID

15163340

Citation

Siegmund, W, et al. "Replacement Therapy With Levothyroxine Plus Triiodothyronine (bioavailable Molar Ratio 14 : 1) Is Not Superior to Thyroxine Alone to Improve Well-being and Cognitive Performance in Hypothyroidism." Clinical Endocrinology, vol. 60, no. 6, 2004, pp. 750-7.
Siegmund W, Spieker K, Weike AI, et al. Replacement therapy with levothyroxine plus triiodothyronine (bioavailable molar ratio 14 : 1) is not superior to thyroxine alone to improve well-being and cognitive performance in hypothyroidism. Clin Endocrinol (Oxf). 2004;60(6):750-7.
Siegmund, W., Spieker, K., Weike, A. I., Giessmann, T., Modess, C., Dabers, T., ... Meng, W. (2004). Replacement therapy with levothyroxine plus triiodothyronine (bioavailable molar ratio 14 : 1) is not superior to thyroxine alone to improve well-being and cognitive performance in hypothyroidism. Clinical Endocrinology, 60(6), pp. 750-7.
Siegmund W, et al. Replacement Therapy With Levothyroxine Plus Triiodothyronine (bioavailable Molar Ratio 14 : 1) Is Not Superior to Thyroxine Alone to Improve Well-being and Cognitive Performance in Hypothyroidism. Clin Endocrinol (Oxf). 2004;60(6):750-7. PubMed PMID: 15163340.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Replacement therapy with levothyroxine plus triiodothyronine (bioavailable molar ratio 14 : 1) is not superior to thyroxine alone to improve well-being and cognitive performance in hypothyroidism. AU - Siegmund,W, AU - Spieker,K, AU - Weike,A I, AU - Giessmann,T, AU - Modess,C, AU - Dabers,T, AU - Kirsch,G, AU - Sänger,E, AU - Engel,G, AU - Hamm,A O, AU - Nauck,M, AU - Meng,W, PY - 2004/5/28/pubmed PY - 2004/8/21/medline PY - 2004/5/28/entrez SP - 750 EP - 7 JF - Clinical endocrinology JO - Clin. Endocrinol. (Oxf) VL - 60 IS - 6 N2 - OBJECTIVES: There is evidence from recent controlled clinical studies that replacement therapy of hypothyroidism with T4 in combination with a small amount of T3 may improve the well-being of the patients. As the issue is still the subject of controversial discussion, our study was assigned to confirm the superiority of a physiological combination of thyroid hormones (absorbed molar ratio 14 : 1) over T4 alone with regard to mood states and cognitive functioning. DESIGN AND PATIENTS: After a run-in period with the T4 study medication for 4 weeks, a controlled, randomized, double-blind, two-period (each 12 weeks), cross-over study without washout between the treatment periods was performed in 23 hypothyroid patients (three males, 20 females, age 23-69 years, 21 subjects after surgery/radioiodine, two with autoimmune thyroiditis) to compare the effects of the previous individual T4 dose (100-175 micro g) with a treatment in which 5% of the respective T4 dose was substituted by T3. MEASUREMENTS: Standard hormonal characteristics and standardized psychological tests to quantify mood and cognitive performance were measured after the run-in period and at the end of each treatment period. In 12 subjects, the concentration-time profiles of fT3 and fT4 were compared after the last administration of the respective study medication. TSH, fT3 and fT4 were measured with immunological assays. CLINICAL RESULTS: Replacement therapy with T4 and T4/T3 was not different in all steady-state hormonal, metabolic and cardiovascular characteristics except for TSH, which was more suppressed after T4/T3. The efficacy of replacement therapy with the T4/T3 combination was not different from the T4 monotherapy with regard to all psychological test scores describing mood and cognitive functioning of the patients. Mood was even significantly impaired by the T4/T3 combination in eight subjects, with TSH < 0.02 mU/l, compared to patients with normal TSH (Beck Depression Inventory: 8.25 +/- 5.01 vs. 4.07 +/- 5.60, P = 0.026). PHARMACOKINETIC RESULTS: The area under the concentration-time curve (AUC(0-8h)) of fT3 was significantly higher after T4/T3 compared to the T4 monotherapy (42.8 +/- 9.03 pmol x h/l vs. 36.3 +/- 8.50 pmol x h/l, P < 0.05) and was significantly correlated to serum TSH (r(s) = -0.609, P < 0.05). After T4/T3, patients with a history of Graves' disease or autoimmune thyroiditis had significantly higher serum trough levels of fT3 whereas the fT4 concentrations were significantly lower in patients with a nonautoimmune background. CONCLUSION: Replacement therapy of hypothyroidism with T4 plus T3 does not improve mood and cognitive performance compared to the standard T4 monotherapy. There is even a higher risk of signs of subclinical hyperthyroidism associated with impaired well-being of the patients, which is clearly caused by significant fluctuations in the steady-state fT3 serum concentrations. SN - 0300-0664 UR - https://www.unboundmedicine.com/medline/citation/15163340/Replacement_therapy_with_levothyroxine_plus_triiodothyronine__bioavailable_molar_ratio_14_:_1__is_not_superior_to_thyroxine_alone_to_improve_well_being_and_cognitive_performance_in_hypothyroidism_ L2 - https://onlinelibrary.wiley.com/resolve/openurl?genre=article&amp;sid=nlm:pubmed&amp;issn=0300-0664&amp;date=2004&amp;volume=60&amp;issue=6&amp;spage=750 DB - PRIME DP - Unbound Medicine ER -