FT3 may be better than FT4 in setting therapy levels.

[diogenes]

This new paper indicates FT3 may be a useful measurement in treated hypothyroidism rather than FT4. Still falls into the trap of preferring normal TSH. Downloadable.

Proportion of serum thyroid hormone concentrations within the reference ranges in athyreotic patients on levothyroxine monotherapy: a retrospective study

May 2022 Thyroid Research 15(1):9

DOI: 10.1186/s13044-022-00127-3

Mitsuru Ito, Sawako Takahashi, Mikiko Okazaki-Hada et al

Abstract and figures

Background In patients receiving thyroid-stimulating hormone (TSH) suppressive therapy with levothyroxine (LT4) after total thyroidectomy for thyroid cancer, thyroid function tests should be performed to adjust the LT4 dose. Specifically, serum TSH concentrations are commonly measured because TSH suppression is necessary according to thyroid cancer risk. The aim of the present study was to elucidate whether free thyroxine (FT4) or free triiodothyronine (FT3) indicates better for adjusting the dose in athyreotic patients on LT4 monotherapy after total thyroidectomy. Methods We retrospectively studied the compatibility of free thyroid hormone (FT4 and FT3) concentrations with reference ranges in athyreotic patients on LT4 monotherapy after total thyroidectomy. Results We identified 2210 consecutive patients from their medical records. Of these patients, 250 had both FT4 and FT3 concentrations in addition to TSH. Two hundred seven had serum TSH concentrations below the reference range (0.5–5.0 μIU/mL), while 43 had them within the reference range. In the 207 patients with TSH concentrations below the reference range, 61 patients (29.5%) had FT4 concentrations within the reference range (0.9–1.7 ng/dL) and 146 patients (70.5%) had FT4 concentrations above the reference range. In contrast, 10 patients (4.8%) had FT3 concentrations below the reference range (2.3–4.0 pg/mL) and 8 (3.9%) had FT3 concentrations above the reference range; 189 patients (91.3%) had concentrations within the reference range. Of the 43 patients with TSH concentrations within the reference range, 25 (58.1%) had FT4 concentrations within the reference range and 18 (41.9%) had FT4 concentrations above the reference range. While, 11 patients (25.6%) had FT3 concentrations below the reference range and one (2.3%) had FT3 concentrations above the reference range; hence, 31 patients (72.1%) had FT3 concentrations within the reference range. Conclusion This study showed that measuring FT3 concentrations rather than FT4 concentrations as the subsequent parameter of thyroid function might be more useful for disease management in terms of the proportion of serum thyroid hormone concentrations within the reference ranges. Furthermore, FT3 measurement could be useful in providing more detailed treatments, including avoiding more aggressive TSH suppressive therapy and identifying the presence of low T3 syndrome in the background.

[Charlie-Farley]

I couldn’t help but laugh when I saw the title.

So they are slowly crawling their way to the truth. Very slowly…… thank you diogenes (keep pushing)

[shaws Administrator]

Thanks for posting and I trialled 'options' when levo was causing awful symptoms thanks to TUK before this forum was started.

My symptoms all resolved on T3 alone.

[DippyDame]

Earlier post by helvella with more replies.

healthunlocked.com/thyroidu...

[Jokaah]

Test