The effect of levothyroxine and selenomethionine on lymphocyte and monocyte cytokine release in women with Hashimoto's thyroiditis

J Clin Endocrinol Metab. 2011 Jul;96(7):2206-15. doi: 10.1210/jc.2010-2986. Epub 2011 Apr 20.


Context: No previous study determined monocyte- and lymphocyte-suppressing effects of levothyroxine and selenomethionine and assessed whether their coadministration is superior to treatment with only one of these drugs.

Objective: Our objective was to compare the effect of levothyroxine and selenomethionine on monocyte and lymphocyte cytokine release and systemic inflammation in patients with Hashimoto's thyroiditis.

Design, setting, participants, and intervention: We conducted a randomized clinical trial involving a group of 170 ambulatory euthyroid women with recently diagnosed and previously untreated Hashimoto's thyroiditis and 41 matched healthy subjects. Participants were randomized in a double-blind fashion to receive a 6-month treatment with levothyroxine, selenomethionine, levothyroxine plus selenomethionine, or placebo. One hundred sixty-five patients completed the study.

Main outcome measures: Monocyte and lymphocyte release of proinflammatory cytokines and plasma levels of C-reactive protein (CRP) were assessed.

Results: Compared with the control subjects, monocytes and lymphocytes of Hashimoto's thyroiditis patients released greater amounts of all cytokines studied. Levothyroxine reduced monocyte release of TNF-α, IL-1β, IL-6, and monocyte chemoattractant protein-1, whereas selenomethionine inhibited lymphocyte release of IL-2, interferon-γ, and TNF-α, which was accompanied by a reduction in plasma CRP levels. The decrease in cytokine release and in plasma CRP levels was strongest when both drugs were given together.

Conclusions: Despite affecting different types of inflammatory cells, levothyroxine and selenomethionine exhibit a similar systemic antiinflammatory effect in euthyroid females with Hashimoto's thyroiditis. This action, which correlates with a reduction in thyroid peroxidase antibody titers, may be associated with clinical benefits in the prevention and management of Hashimoto's thyroiditis, particularly in subjects receiving both agents.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • C-Reactive Protein / metabolism
  • Cytokines / blood*
  • Female
  • Hashimoto Disease / blood
  • Hashimoto Disease / drug therapy*
  • Humans
  • Lymphocytes / drug effects*
  • Lymphocytes / metabolism
  • Middle Aged
  • Monocytes / drug effects*
  • Monocytes / metabolism
  • Selenomethionine / pharmacology*
  • Selenomethionine / therapeutic use
  • Thyroxine / pharmacology*
  • Thyroxine / therapeutic use


  • Cytokines
  • C-Reactive Protein
  • Selenomethionine
  • Thyroxine