A 28-year-old male asked:
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what would cause a low t3 (liothyronine) level but normal tsh and t4 levels? would that be considered hypothyroidism?

2 doctor answers
Dr. Terri Washington
15 years experience Endocrinology
No: Low t3 (liothyronine) with nl TSH and T4 is not hypothyroidism. Many things can make t3 (liothyronine) levels decrease such as illness, stress, colds etc. It is nonspecific and could also be lab error so low t3 (liothyronine) in the face of nl TSH and free T4 levels does not mean very much.
Answered on Jan 15, 2015
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Dr. Robin Merlino
40 years experience Internal Medicine
Birth control pills: If your TSH is normal you are not hypothyroid. T4 is converted to t3 (liothyronine) in your cells. The blood test measures t3 (liothyronine) that is bound to a protein in your blood and the active form of t3 (liothyronine). If you have too much or too little of the protein it can change the value of t3 (liothyronine). Birth control pills as well as other meds can effect the value.
Answered on Jun 10, 2014
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