4 doctors weighed in:

I have hypothyroidism so can you explain to me in detail why my T3 (liothyronine) is normal while my T4 and TSH are low?

4 doctors weighed in
Dr. Liuska Pesce
Pediatrics - Endocrinology
1 doctor agrees

In brief: It is complex

Low TSH and low T4 usually means hypothyroidism due to a problem with the tsh-secreting pituitary gland or hypothalamus.
The treatment is to replace t4. It is important to make sure you make cortisol before this is done. T3 (liothyronine) is the more active form of thyroid hormone and comes from the conversion of T4 to t3 (liothyronine). I would recommend you see and discuss your results with an expert in thyroid disorders.

In brief: It is complex

Low TSH and low T4 usually means hypothyroidism due to a problem with the tsh-secreting pituitary gland or hypothalamus.
The treatment is to replace t4. It is important to make sure you make cortisol before this is done. T3 (liothyronine) is the more active form of thyroid hormone and comes from the conversion of T4 to t3 (liothyronine). I would recommend you see and discuss your results with an expert in thyroid disorders.
Dr. Liuska Pesce
Dr. Liuska Pesce
Thank
Dr. Phillip Sirota
Internal Medicine
1 doctor agrees

In brief: Free T4 best test

T3 (liothyronine) + T4 is the total thyroxine level.
Free T4 is the active thyroxine and the best test to determine if you are hypothyroid vs hyperthyroid at any point in time. Tsh is a marker but takes several weeks to adjust to new thyroid levels. Tsh should be the only test used to guide dosage of levothyroxine in most patients.

In brief: Free T4 best test

T3 (liothyronine) + T4 is the total thyroxine level.
Free T4 is the active thyroxine and the best test to determine if you are hypothyroid vs hyperthyroid at any point in time. Tsh is a marker but takes several weeks to adjust to new thyroid levels. Tsh should be the only test used to guide dosage of levothyroxine in most patients.
Dr. Phillip Sirota
Dr. Phillip Sirota
Thank
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