thyroid levels

in by owlbutterfly

what does it mean when tsh is low and ft4 is high.
1.94 ng/dL 0.59-1.17 completed H 06/13/2016
Lab Report: TSH – 06/13/2016
<0.02 mIU/L 0.34-4.82 completed L 06/13/2016

About owlbutterfly

Conditions: Hashimoto's thyroid disease

Doctors seen: MD – primary care

Age: 45-54


1 Answer


When your free T4 is high and your TSH is low, that means that you are hyperthyroid. Hyperthyroid means that you have too much thyroid hormone being produced (or you are on too much thyroid medication and it needs to be lowered).

The thyroid produces 2 hormones – T3 and T4 – naturally. The most active of the two is T3, which is what is used in the body for various functions. T4 is an inactive form, but it is not broken down as quickly as T3, so more of it is produced in the thyroid gland and then transported to the surrounding tissues where it is converted to T3, which can be used.

TSH (also known as thyroid stimulating hormone) is produced in the pituitary gland in response to low thyroid hormone levels (T3 and T4) in the blood stream. When there is low T3 and T4 in the blood stream, TSH is produced in the pituitary, and then travels to the thyroid gland, where it stimulates thyroid hormone production in the thyroid gland. When there is high T4 and T3 in the blood stream, it suppresses TSH from being produced in the pituitary, which then inhibits the ability of thyroid hormone from being produced in the thyroid gland so that blood levels of thyroid hormone can lower naturally.

Hyperthyroidism though can be caused by a number of things. There are 2 main causes of hyperthyroidism. The first is an autoimmune disease called Graves’ disease, which causes an over production of thyroid hormone in the gland, despite the levels of TSH. The other way is that there is too much medication that is being taken (synthroid or cytomel) that is causing suppression of the TSH.

If you have high thyroid hormone levels, this should be managed by a physician that is familiar with thyroid hormone production and symptoms, so that proper causes can be ruled out.

Jenny Bennett, ND LAc

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Answered on November 6, 2016

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