Does Substitution of T4 with T3 Plus T4 for T4 Replacement Improve Depressive Symptoms in Patients with Hypothyroidism?

Substitution of T4 with T3 for T4 replacement in patients with hypothyroidism was undertaken using a randomized placebo controlled study design. Forty individuals were included who had depressive symptoms on stable doses of levothyroxine. Combined T4 plus T3 did not have a significantly different effect on mood and well-being scores than did T4 alone.