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Thyroxine plus triiodothyronine and thyroxine alone have similar effects in patients with hypothyroidism
The background of the study. Patients
with hypothyroidism who are treated with thyroxine (T4) may not
feel well. Treatment with T4 plus triiodothyronine (T3) has not
proven more effective, but in most studies the patients were given
an arbitrary dose of T3. In this study the effects of T4 alone were
compared with a combination of T4 plus T3 in which the ratio of
T4:T3 was estimated to be the same as that secreted by the normal
thyroid.
How the study was done. The study subjects were 26 patients with hypothyroidism treated with 100 to 175 µg of T4 daily. They were treated with their usual dose of T4, given once daily in locally prepared capsules, for four weeks. Then they were given, in random order for 12 weeks, capsules containing their usual T4 dose or capsules containing 95 percent of that dose as T4 and 5 percent as T3. At the end of each treatment period, multiple psychological and cognitive-function tests were administered.
The results of the study. There were no differences in heart rate, blood pressure, or biochemical values at the end of the 12-week treatment periods, except that the mean serum TSH concentration was lower and more patients had undetectable serum TSH concentrations at the end of the T4-plus-T3 period. There were no differences in the results of the tests of mood, anxiety, other psychopathology, well-being, or cognitive function at the end of the two treatment periods.
The conclusions of the study. In patients with hypothyroidism, combination therapy with T4 and T3 does not improve mood, general well-being, or cognitive function more than therapy with T4 alone.
The original article. Siegmund W,
Spieker K, Weike AI, Giessmann T, Modess C, Dabers T, Kirsch G,
Sanger E, Engel G, Hamm AO, Nauck M, Meng W. 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;60:750-7.
Next Article: Serum triiodothyronine concentrations change
less after sustained-release triiodothyronine than standard
triiodothyronine
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| Thyroid Digest Index | | | July 2004 Thyroid Digest |
