The timing of TFTs, whether fasting, postprandial, or random, remains a debated issue. Assay interference and biotin intake should be considered when analyzing TFTs. The role of iodine and iodine supplementation during pregnancy and its impact on STDs are not yet fully conceptualized. Large randomized clinical and epidemiological studies are needed to establish a consensus on the diagnostic threshold for TSH. These studies should include diverse populations and medical conditions to improve our understanding of the disease and patient outcomes. In practice, avoid rushing to treat elevated TSH levels between 4 and 10 mIU/L or low TSH between 0.5 and 0.1 mIU/L without confirming the diagnosis with additional tests (T3, T4, FT4, FT3, and TPO). TSH alone should not be the sole decision-maker; consider other TFTs and sequential testing from the same laboratory and time to make more informed decisions. While TSH levels can be affected by time and prandial state, FT3 and FT4 levels remain stable, suggesting all three TFTs may aid in accurate diagnosis and treatment decisions.
Rajesh Agrawal (2026) studied this question.