TSH and thyroid hormones concentrations in patients with hypothyroidism receiving replacement therapy with L-thyroxine alone or in combination with L-triiodothyronine.
The aim of this study was to evaluate parameters of thyroid function in patients with primary hypothyroidism receiving either monotherapy with L-T4 or combination L-T4+L-T3. Fifty-eight women with primary hypothyroidism receiving L-T4 were enrolled in the study. The patients were randomised into two groups: Group 1 (n=42) patients continued monotherapy with L-T4, and Group 2 (n=16) patients were switched to combined therapy with L-T4+L-T3 (25 microg L-T4 was replaced with 12.5 microg L-T3). The final examination was carried out 6 months thereafter. There was also a third group of 20 healthy women (control group). Under monotherapy with L-T4, serum FT4 levels were higher (p < 0.05) and FT3 lower (p < 0.05) than in the control group, while the monotherapy subgroup of patients with low-normal TSH had serum FT4 levels higher than in the control group (p < 0.05). Serum FT4 under combined therapy was significantly lower than in both control and monotherapy groups. FT3 levels did not differ between the two groups of combined and monotherapy subjects; the highest FT3 levels were in the control group. L-T4 replacement therapy is associated with non-physiologically high FT4 and low FT3 levels. Therapy with L-T3 once a day does not simulate the normal production of T3 by the thyroid.
Fadeyev
Valentin V
VV
Department of Endocrinology of Moscow Medical Academy, Moscow, 119992, Russia. walfad@nccom.ru
Morgunova
Tatiana B
TB
Sytch
Julia P
JP
Melnichenko
Galina A
GA
D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000097:blood* / Q000188:drug therapy*; D013963:Thyroid Hormones / Q000097:blood*; D013972:Thyrotropin / Q000097:blood*; D013974:Thyroxine / Q000008:administration & dosage* / Q000097:blood; D014284:Triiodothyronine / Q000008:administration & dosage* / Q000097:blood
D013963:Thyroid Hormones; D014284:Triiodothyronine; D013972:Thyrotropin; D013974:Thyroxine