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Is Treatment With T3 Containing Preparations Advisable When T3-T4 Combination Preparations Fail?
Question: Ater t 4 fail , should I try t3 ?
Brief Answer:
Generally no
Detailed Answer:
T3 is generally not recommended by thyroid experts as it is deemed unsafe
Thyroid hormone preparations containing T3 alone or in combination with T4 include the following : T3 alone (eg, Cytomel), T4-T3 combination preparations (eg, Thyrolar), and desiccated thyroid (a mixture of T3 and T4 made from porcine thyroid glands, eg, Armour Thyroid).
For most patients with hypothyroidism, thyroid specialists (ie endocrinologists) do not suggest treatment with T3 containing preparations. Patients treated with currently available T3-containing preparations have wide fluctuations in blood T3 levels throughout the day due to its rapid absorption from the gut and its relatively short stay in the circulation.
In addition, blood T4 levels remain low in patients treated with T3, and relatively low in those treated with preparations containing both T3 and T4; while serum TSH in steady state conditions will reflect the adequacy of therapy, measurement of serum T4 may be confusing and lead to inappropriate changes in dose.
To put it simply, if one is on T3 treatment, blood test for T4 may appear low. Testing for free T3 levels in blood has limitations because the laboratory method for that is not fully reliable yet.
There are few legitimate uses of T3 nowadays. One example is this : Temporary treatment with T3 is appropriate in patients with thyroid cancer who are to undergo radio-iodine imaging and possible treatment. To shorten the period of hypothyroidism, the patient's T4 therapy is discontinued and T3 is substituted for three to four weeks until the T4 is cleared
Generally no
Detailed Answer:
T3 is generally not recommended by thyroid experts as it is deemed unsafe
Thyroid hormone preparations containing T3 alone or in combination with T4 include the following : T3 alone (eg, Cytomel), T4-T3 combination preparations (eg, Thyrolar), and desiccated thyroid (a mixture of T3 and T4 made from porcine thyroid glands, eg, Armour Thyroid).
For most patients with hypothyroidism, thyroid specialists (ie endocrinologists) do not suggest treatment with T3 containing preparations. Patients treated with currently available T3-containing preparations have wide fluctuations in blood T3 levels throughout the day due to its rapid absorption from the gut and its relatively short stay in the circulation.
In addition, blood T4 levels remain low in patients treated with T3, and relatively low in those treated with preparations containing both T3 and T4; while serum TSH in steady state conditions will reflect the adequacy of therapy, measurement of serum T4 may be confusing and lead to inappropriate changes in dose.
To put it simply, if one is on T3 treatment, blood test for T4 may appear low. Testing for free T3 levels in blood has limitations because the laboratory method for that is not fully reliable yet.
There are few legitimate uses of T3 nowadays. One example is this : Temporary treatment with T3 is appropriate in patients with thyroid cancer who are to undergo radio-iodine imaging and possible treatment. To shorten the period of hypothyroidism, the patient's T4 therapy is discontinued and T3 is substituted for three to four weeks until the T4 is cleared
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Above answer was peer-reviewed by :
Dr. Chakravarthy Mazumdar
Answered by
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