Proportion of patients with apparently sufficient T4 in therapy and consequent ranges of FT4 and FT3.

[diogenes]

This downloadable paper recently out examines the FT4/3 results for patients on T4 therapy. Good paper from a respected Japanese thyroidologist.

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

May 2022Thyroid Research 15(1):9

DOI: 10.1186/s13044-022-00127-3

LicenseCC BY 4.0

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

[Star13]

Here is a link to the paper:

thyroidresearchjournal.biom...

[Gingernut44]

Thanks for posting, we just need those with the “power” to read and inwardly digest 🤨

[mfinn]

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. Hallelujah!!!

[tattybogle]

"We reported that athyreotic patients receiving LT4 with mild TSH suppression and FT4 concentrations above the reference range but normal FT3 concentrations, metabolic indicators [9], and physical symptoms [10] were in a euthyroid state.

In contrast, athyreotic patients with complete TSH suppression that resulted in both FT4 and FT3 concentrations above the reference range, metabolic indicators [9], and physical symptoms [10] were in a thyrotoxic state.

These data suggest that among athyreotic patients receiving LT4, patients with mildly suppressed TSH and normal FT3 concentrations were closest to the euthyroid state, whereas those with completely suppressed TSH concentrations and FT3 concentrations above the reference range were in the thyrotoxic state.

Therefore, in patients with TSH suppression receiving LT4 after total thyroidectomy, determination of serum FT3 and TSH concentrations may be useful to avoid thyrotoxicosis."

[Hoxo]

What’s quite startling with the paper’s data is how few people actually fit the ‘TSH in range’ therefore ‘T4 and T3’ should be Ok assumption.

[BB001]

No mention of people who have suppressed TSH but fT3 low in range i.e. the poor converters of T4 to T3.