Objective: We and others recently reported that in total thyroidectomy (TT), serum triiodothyronine (T 3 ) levels during levothyroxine (L-T 4 ) therapy were low compared to the preoperative levels, suggesting that the presence of the thyroid tissue affects the balances of serum thyroid hormone levels. However, the effects of remnant thyroid tissue on these balances in thyroidectomized patients have not been established. Methods: We retrospectively studied 253 euthyroid patients with papillary thyroid carcinoma who underwent a TT or hemithyroidectomy (HT). We divided the cases into the TTCsupplemental L-T 4 (CL-T 4 ) group (nZ103); the HTCL-T 4 group (nZ56); and the HT-alone group (nZ94). We compared the postoperative serum levels of free T 4 (FT 4 ) and free T 3 (FT 3 ) and the FT 3 /FT 4 ratio in individual patients with those of controls matched by serum TSH levels. Results: The TTCL-T 4 group had significantly higher FT 4 (P!0.001), lower FT 3 (P!0.01) and lower FT 3 /FT 4 (P!0.001) levels compared to the controls. The HTCL-T 4 group had FT 4 , FT 3 and FT 3 /FT 4 levels equivalent to those of the controls. The HT-alone group had significantly lower FT 4 (P!0.01), equivalent FT 3 (PZ0.083), and significantly higher FT 3 /FT 4 (P!0.001) ratios than the controls. Conclusions: The presence of the remnant thyroid tissue was associated with different thyroid hormone balances in thyroidectomized patients, suggesting that T 3 production by remnant thyroid tissue has a substantial effect on the maintenance of postoperative serum T 3 levels.

Early onset of thyrotoxicosis postpartum was associated mainly with PPDT, and a late onset was suggestive of PPGr. Positive TRAb and high TBF >4.0% are indicators of postpartum onset of Graves' disease.

Infertile women sometimes associated with subclinical hypothyroidism (SCH). The guidelines of the American Endocrine Society, and American Association of Clinical Endocrinologists and American Thyroid Association recommend treatment with thyroxine (T4) for patients with SCH who want to have children. We examined 69 female infertile patients with SCH and the effects of levothyroxine (l-T4) therapy on pregnancy rates and pregnancy outcomes were observed. Fifty-eight (84.1%) patients successfully conceived during the T4 treatment period (Group A), although 17 patients (29.3%) had miscarriage afterward. The remaining 11 patients continued to be infertile (Group B). The median TSH value in Group A before the T4 treatment was 5.46 μIU/mL (range 3.1-13.3) and this significantly decreased to 1.25 μIU/mL (range 0.02-3.75) during the treatment (p<0.001). The estimated duration of infertility before the T4 treatment was 2.8±1.7 years and the duration until pregnancy after the treatment was significantly shorter at 0.9±0.9 years (p<0.001). Shortening of the infertile period after the T4 therapy was observed not only in patients who were treated with assisted reproductive technology (ART) but also in patients who conceived spontaneously in Group A. Administered T4 dose was 54.3±14.2 μg before pregnancy and 68.5±22.8 μg during pregnancy (p<0.001). Anti-thyroid autoantibodies were identified in 42.0% of all patients and no significant difference was observed in positivity between Group A and Group B. High successful pregnancy rate and shorter duration of infertility until pregnancy after T4 treatment strongly suggest that T4 enhanced fertility in infertile patients with SCH.

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