Why your thyroid might act weird if you don't get enough selenium
Thyroid function in patients with selenium deficiency exhibits high free T4 to T3 ratio
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
TSH levels didn’t rise consistently—even when T3 dropped and T4 rose.
Everyone assumes low T3 triggers high TSH—but here, the pituitary didn’t respond, suggesting the body’s feedback loop is disrupted at the tissue level, not the gland level.
Practical Takeaways
If you have unexplained fatigue, brain fog, or hair loss—and your TSH is normal—ask your doctor for a free T3, free T4, and FT4/FT3 ratio test.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
TSH levels didn’t rise consistently—even when T3 dropped and T4 rose.
Everyone assumes low T3 triggers high TSH—but here, the pituitary didn’t respond, suggesting the body’s feedback loop is disrupted at the tissue level, not the gland level.
Practical Takeaways
If you have unexplained fatigue, brain fog, or hair loss—and your TSH is normal—ask your doctor for a free T3, free T4, and FT4/FT3 ratio test.
Publication
Journal
Clinical Pediatric Endocrinology
Year
2021
Authors
Ryohei Kobayashi, M. Hasegawa, C. Kawaguchi, N. Ishikawa, K. Tomiwa, M. Shima, K. Nogami
Related Content
Claims (6)
The body converts the thyroid hormone T4 into its active form, T3, using enzymes that require selenium as a component.
In people with low selenium levels, taking selenium supplements lowers free T4 and the ratio of free T4 to free T3 while raising free T3 levels, suggesting that selenium plays a role in how the body converts thyroid hormones and that this process can improve with supplementation.
In people with low selenium levels from limited food intake or nutritional support, a specific blood ratio of thyroid hormones (free T4 to free T3) is higher than in people with normal selenium levels, which may help detect selenium deficiency before symptoms appear.
In people with very low selenium levels, lower selenium amounts are linked to a higher ratio of inactive thyroid hormone (FT4) to active thyroid hormone (FT3), indicating that selenium deficiency may reduce the body’s ability to convert FT4 into FT3.
People with low selenium levels have lower amounts of free T3 hormone in their blood compared to those with normal thyroid function, but their free T4 and TSH levels do not consistently rise, suggesting the issue is not with the thyroid gland itself but with how the body converts thyroid hormones in peripheral tissues.