From the Research
A T3 uptake of 28% is below the normal reference range, suggesting potential thyroid dysfunction, and I strongly recommend consulting with a healthcare provider promptly for a complete thyroid panel, as this isolated result is insufficient for diagnosis. This low value indicates decreased binding capacity of thyroid hormone transport proteins, which often occurs in hypothyroidism. According to a recent study 1, hypothyroidism is a relatively common condition that generally cannot be reversed, and levothyroxine therapy provides satisfactory treatment for most patients. However, a subset of patients may not be restored to their baseline quality of life, and combination therapy with levothyroxine and liothyronine may be considered.
Some key points to consider:
- T3 uptake alone is insufficient for diagnosis, and additional thyroid function tests like TSH, free T4, and free T3 are necessary for proper evaluation.
- Low T3 uptake can be caused by various conditions, including primary hypothyroidism, pituitary dysfunction, protein abnormalities, or certain medications.
- Modern thyroid testing has largely replaced T3 uptake with more direct measurements of thyroid hormones, so the healthcare provider may use different tests for follow-up assessment.
- A study published in 2021 2 noted that a number of randomized, controlled trials have failed to demonstrate superiority for combination therapy, largely due to non-physiological T3 doses, but patients with hypothyroidism are highly heterogeneous, and individualized treatment approaches may be necessary.
- Another study published in 2021 3 provided Consensus Statements to guide the development of future clinical trials of LT4/LT3 combination therapy, including the use of patient-reported outcomes as a primary outcome and patient preference as a secondary outcome.
It's essential to note that the healthcare provider may order additional tests to determine if thyroid hormone replacement therapy is needed, and no immediate medication is indicated based solely on this isolated result. The most recent and highest-quality study 1 suggests that future efforts to improve hypothyroidism therapy could focus on identifying the specific subset of patients who benefit from combination therapy and understanding the drivers of patient preference for combination therapy.