Association between serum thyroid hormone balance and thyroid volume in patients treated with levothyroxine monotherapy for hypothyroidism

Many previous studies including ours have reported that athyreotic patients on levothyroxine (LT4) relatively low serum free triiodothyronine (FT3) levels, whereas with large goitrous diseases often high FT3 levels. Here we investigated Hashimoto thyroiditis (HT) LT4 to study the relationship between thyroid volume (TV) and hormone status in hypothyroid LT4. We retrospectively studied 408 euthyroid HT treated for hypothyroidism; divided them as per TV compared levels of thyroxine (FT4) FT3/FT4 ratio each patient group those matched control group. also evaluated association level among In <15 mL, were significantly lower than controls. 15–80 equivalent ≥80 higher The (r = 0.35, p < 0.01) 0.42, showed a positive correlation TV. TVs caused differences balance, increasing increases ratio. Serum balance smaller thyroids was similar patients. Mild thyrotropin suppression is needed achieve normal such