A specific dosage equivalency exists between T4 and T3 thyroid hormones
the verdict
SUPPORTED
the evidence backs this
confidence 92/100
Clinical guidelines and pharmacological studies establish that specific dosage equivalencies and ratios exist when substituting or combining T4 (levothyroxine) and T3 (liothyronine) thyroid hormones.
Evidence for · 2
2012 ETA Guidelines: The Use of L-T4 + L-T3 in the Treatment of Hypothyroidism
2012 · cited by 429
The 2012 ETA guidelines suggest starting combination therapy with an L-T4/L-T3 dose ratio by weight between 13:1 and 20:1.
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More for · 1
The pharmacodynamic equivalence of levothyroxine and liothyronine: a randomized, double blind, cross‐over study in thyroidectomized patients
2010 · cited by 63
A clinical study in thyroidectomized patients demonstrated that the therapeutic substitution of L-T3 for L-T4 was achieved at approximately a 3:1 weight ratio (or roughly 1:3 ratio for T3:T4).