Far, far too small a group. Why the chosen T4:T3 dosing regime? For some, a halfing of dose from 150 T4 to 75 with the addition of 15 T3. I can't see that being appropriate. (Odd to reduce the dose of some by by 50 and others by 75, don't you think?)
No identification of how they felt before. Quite likely, despite their stable doses, some would have been under-treated and some over-treated.
I don't get this bit at all:
... TSH and T3 levels were not affected by type of therapy. More patients on LT4/LT3 had T3 levels above the upper limit ...
Not affected followed by the effect! Am I totally mis-reading it?
Arch Endocrinol Metab. 2016 Nov-Dec;60(6):562-572. doi: 10.1590/2359-3997000000192. Epub 2016 Aug 25.
Treatment of hypothyroidism with levothyroxine plus liothyronine: a randomized, double-blind, crossover study.
Kaminski J1, Miasaki FY1, Paz-Filho G2, Graf H1, Carvalho GA1.
1Serviço de Endocrinologia e Metabologia (SEMPR), Departamento de Medicina Interna, Hospital das Clínicas da Universidade Federal do Paraná (HC-UFPR), Curitiba, PR, Brasil.
2Genome Sciences Department, The John Curtin School of Medical Research, The Australian National University, Canberra, ACT, Australia.
To compare the effects of a unique fixed combination levothyroxine/liothyronine (LT4/LT3) therapy in patients with primary hypothyroidism.
Subjects and methods:
This is a randomized, double-blind, crossover study. Adults with primary hypothyroidism (n = 32, age 42.6 ± 13.3, 30 females) on stable doses of LT4 for ≥ 6 months (125 or 150 μg/day) were randomized to continue LT4 treatment (G1) or to start LT4/LT3 therapy (75/15 μg/day; G2). After 8 weeks, participants switched treatments for 8 more weeks. Thyroid function, lipid profile, plasma glucose, body weight, electrocardiogram, vital signs, and quality of life (QoL) were evaluated at weeks 0, 8 and 16.
Free T4 levels were significantly lower while on LT4/LT3 (G1: 1.07 ± 0.29 vs. 1.65 ± 0.46; G2: 0.97 ± 0.26 vs. 1.63 ± 0.43 ng/dL; P < 0.001). TSH and T3 levels were not affected by type of therapy. More patients on LT4/LT3 had T3 levels above the upper limit (15% vs. 3%). The combination therapy led to an increase in heart rate, with no significant changes in electrocardiogram or arterial blood pressure. Lipid profile, body weight and QoL remained unchanged.
The combination therapy yielded significantly lower free T4 levels, with no changes in TSH or T3 levels. More patients on LT4/T3 had elevated T3 levels, with no significant alterations in the evaluated outcomes. No clear clinical benefit of the studied formulation could be observed. Future trials need to evaluate different formulations and the impact of the combined therapy in select populations with genetic polymorphisms.